Algebraic Exponents and Radicals

31 soru

Soru 21Soru

If xx and yy are real numbers greater than 11 such that xy=yxx^{\sqrt{y}} = y^{\sqrt{x}} and x3=y2x^3 = y^2, what is the value of xx?

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Cevap: 8116\frac{81}{16}

Cevap

The correct answer is 8116\frac{81}{16}.
Expressing yy as x3/2x^{3/2} and substituting it into xy=yxx^{\sqrt{y}} = y^{\sqrt{x}} transforms the equation into xx3/4=x32x1/2x^{x^{3/4}} = x^{\frac{3}{2}x^{1/2}}. Equating exponents yields x3/4=32x1/2x^{3/4} = \frac{3}{2}x^{1/2}, which simplifies to x1/4=32x^{1/4} = \frac{3}{2}. Raising both sides to the fourth power gives x=8116x = \frac{81}{16}.

Adım Adım Çözüm

1
Express yy in terms of xx using the second given equation.
Since x>1x > 1 and y>1y > 1, taking the square root of both sides of y2=x3y^2 = x^3 gives y=x3/2y = x^{3/2}.
Converting yy to an exponential expression of xx allows single-variable substitution into the first equation.
2
Substitute y=x3/2y = x^{3/2} into the first equation xy=yxx^{\sqrt{y}} = y^{\sqrt{x}}.
Note that y=x3/2=(x3/2)1/2=x3/4\sqrt{y} = \sqrt{x^{3/2}} = (x^{3/2})^{1/2} = x^{3/4}. Thus, the left side becomes xx3/4x^{x^{3/4}}, and the right side becomes (x3/2)x=x32x1/2(x^{3/2})^{\sqrt{x}} = x^{\frac{3}{2}x^{1/2}}.
Applying exponent rules (am)n=amn(a^m)^n = a^{mn} simplifies both sides to base xx expressions.
3
Equate the exponents since the bases are equal and greater than 1.
x3/4=32x1/2x^{3/4} = \frac{3}{2}x^{1/2}.
If xa=xbx^a = x^b for x>1x > 1, then a=ba = b.
4
Divide both sides by x1/2x^{1/2} to isolate the power of xx.
x3/4x1/2=32    x3/41/2=32    x1/4=32\frac{x^{3/4}}{x^{1/2}} = \frac{3}{2} \implies x^{3/4 - 1/2} = \frac{3}{2} \implies x^{1/4} = \frac{3}{2}.
Using the quotient rule for exponents, xaxb=xab\frac{x^a}{x^b} = x^{a-b} where 3/41/2=1/43/4 - 1/2 = 1/4.
5
Raise both sides to the 4th power to solve for xx.
x=(32)4=3424=8116x = \left(\frac{3}{2}\right)^4 = \frac{3^4}{2^4} = \frac{81}{16}.
Raising (x1/4)4(x^{1/4})^4 eliminates the fractional exponent to give xx.

Anahtar Kavram

Solving systems of exponential equations using fractional exponent rules and base equality properties.
Soru 22Soru

If xx and yy are positive real numbers such that (x1y23x3y2)34=xayb\left(\frac{x^{-1}y^{\frac{2}{3}}}{\sqrt{x^3 y^{-2}}}\right)^{-\frac{3}{4}} = x^a y^b, what is the value of a+ba + b?

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Cevap: 58\frac{5}{8}

Cevap

The value of a+ba + b is 58\frac{5}{8}.
Simplifying the fraction inside the parentheses gives x52y53x^{-\frac{5}{2}} y^{\frac{5}{3}}. Raising this to the power of 34-\frac{3}{4} produces x158y54x^{\frac{15}{8}} y^{-\frac{5}{4}}. Equating exponents yields a=158a = \frac{15}{8} and b=54=108b = -\frac{5}{4} = -\frac{10}{8}. Adding these together gives a+b=58a + b = \frac{5}{8}.

Adım Adım Çözüm

1
Rewrite the radical expression in the denominator using fractional exponents.
x3y2=(x3y2)12=x32y1\sqrt{x^3 y^{-2}} = (x^3 y^{-2})^{\frac{1}{2}} = x^{\frac{3}{2}} y^{-1}
Applying the power rule (uv)w=uvw(u^v)^w = u^{v \cdot w} to radical expressions converts square roots to fractional exponents of 12\frac{1}{2}.
2
Simplify the expression inside the main parentheses by combining like base exponents.
\frac{x^{-1}y^{\frac{2}{3}}}{x^{\frac{3}{2}} y^{-1}} = x^{-1 - \frac{3}{2}} y^{\frac{2}{3} - (-1)} = x^{-\frac{5}{2}} y^{\frac{5}{3}}
When dividing exponential expressions with the same base, subtract the denominator exponent from the numerator exponent.
3
Apply the outer exponent 34-\frac{3}{4} to each factor inside the parentheses.
(x^{-\frac{5}{2}} y^{\frac{5}{3}})^{-\frac{3}{4}} = x^{(-\frac{5}{2})(-\frac{3}{4})} y^{(\frac{5}{3})(-\frac{3}{4})} = x^{\frac{15}{8}} y^{-\frac{5}{4}}
According to exponent rules, (uv)p=upvp(u \cdot v)^p = u^p \cdot v^p and (up)q=upq(u^p)^q = u^{p \cdot q}.
4
Identify aa and bb and calculate their sum a+ba + b.
a = \frac{15}{8}, \quad b = -\frac{5}{4} = -\frac{10}{8} \implies a + b = \frac{15}{8} - \frac{10}{8} = \frac{5}{8}
Match the simplified expression with xaybx^a y^b and add the resulting fractional exponents using a common denominator.

Anahtar Kavram

Simplifying nested algebraic expressions with negative and rational exponents using fundamental laws of exponents.
Tahmini Süre:2m 0s
Soru 23Soru

What is the sum of all real solutions to the equation 3x+10x=2\sqrt{3x + 10} - x = 2?

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Cevap: 22

Cevap

The sum of all real solutions is 22.
To solve 3x+10x=2\sqrt{3x + 10} - x = 2, isolate the radical to get 3x+10=x+2\sqrt{3x + 10} = x + 2. Squaring both sides yields 3x+10=x2+4x+43x + 10 = x^2 + 4x + 4. Rearranging into standard quadratic form gives x2+x6=0x^2 + x - 6 = 0, which factors as (x+3)(x2)=0(x + 3)(x - 2) = 0, yielding candidates x=2x = 2 and x=3x = -3. Substituting x=2x = 2 into the original equation yields 162=2\sqrt{16} - 2 = 2, which is true. Substituting x=3x = -3 yields 1(3)=42\sqrt{1} - (-3) = 4 \neq 2, so x=3x = -3 is extraneous. The only valid solution is x=2x = 2, so the sum of all valid solutions is 22.

Adım Adım Çözüm

1
Isolate the radical expression on one side of the equation
3x+10=x+2\sqrt{3x + 10} = x + 2
Isolating the radical allows squaring both sides cleanly to eliminate the radical sign.
2
Square both sides of the equation
3x+10=(x+2)2=x2+4x+43x + 10 = (x + 2)^2 = x^2 + 4x + 4
Squaring eliminates the square root, converting the equation into a polynomial form.
3
Rearrange terms into standard quadratic form ax2+bx+c=0ax^2 + bx + c = 0
x2+x6=0x^2 + x - 6 = 0
Grouping all terms on one side sets up the equation for factoring.
4
Factor the quadratic equation to find candidate solutions
(x+3)(x2)=0    x=3 or x=2(x + 3)(x - 2) = 0 \implies x = -3 \text{ or } x = 2
Factoring determines the values of xx that solve the algebraic polynomial.
5
Test candidate solutions in the original radical equation to filter extraneous roots
For x=2x = 2: 3(2)+102=162=42=2\sqrt{3(2) + 10} - 2 = \sqrt{16} - 2 = 4 - 2 = 2 (Valid). For x=3x = -3: 3(3)+10(3)=1+3=42\sqrt{3(-3) + 10} - (-3) = \sqrt{1} + 3 = 4 \neq 2 (Extraneous). Thus, x=2x = 2 is the only valid solution.
Squaring an equation can introduce extraneous roots that do not satisfy the original principal root definition.

Anahtar Kavram

Solving Radical Equations and Filtering Extraneous Roots
Tahmini Süre:1m 30s
Soru 24Soru

Let PP be the product of all positive real numbers xx that satisfy the exponential equation xx=(x2x)xx^{\sqrt{x}} = \left(x^2\sqrt{x}\right)^x. What is the value of PP?

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Cevap: 425\frac{4}{25}

Cevap

425\frac{4}{25}
Simplifying the right-hand side yields xx=x52xx^{\sqrt{x}} = x^{\frac{5}{2}x}. For x=1x = 1, both sides equal 1, making x=1x = 1 a valid solution. For x>0x > 0 and x1x \neq 1, equating the exponents gives x=52x\sqrt{x} = \frac{5}{2}x, which reduces to x=25\sqrt{x} = \frac{2}{5}, so x=425x = \frac{4}{25}. Multiplying all valid solutions together yields 1425=4251 \cdot \frac{4}{25} = \frac{4}{25}.

Adım Adım Çözüm

1
Simplify the right-hand side of the equation using fractional exponent rules.
Since x2x=x2x1/2=x5/2x^2\sqrt{x} = x^2 \cdot x^{1/2} = x^{5/2}, the equation becomes xx=(x5/2)x=x52xx^{\sqrt{x}} = \left(x^{5/2}\right)^x = x^{\frac{5}{2}x}.
Combining terms with the same base into a single exponent simplifies comparison between both sides.
2
Check for the base root x=1x = 1.
Substituting x=1x = 1 gives 11=11=11^{\sqrt{1}} = 1^1 = 1 and (121)1=11=1(1^2\sqrt{1})^1 = 1^1 = 1. Thus, x=1x = 1 is a valid solution.
For any exponential equation of the form xf(x)=xg(x)x^{f(x)} = x^{g(x)}, x=1x = 1 is always a candidate solution because 1a=1b=11^a = 1^b = 1 for all real exponents.
3
Equate the exponents for positive real solutions where x1x \neq 1.
Setting the exponents equal gives x=52x\sqrt{x} = \frac{5}{2}x.
When the base x>0x > 0 and x1x \neq 1, xf(x)=xg(x)x^{f(x)} = x^{g(x)} implies f(x)=g(x)f(x) = g(x).
4
Solve the resulting radical equation for xx.
Divide both sides by x\sqrt{x} (since x>0x > 0): 1=52x    x=25    x=(25)2=4251 = \frac{5}{2}\sqrt{x} \implies \sqrt{x} = \frac{2}{5} \implies x = \left(\frac{2}{5}\right)^2 = \frac{4}{25}.
Isolating x\sqrt{x} and squaring both sides gives the non-trivial solution.
5
Compute the product PP of all positive real solutions.
P=1425=425P = 1 \cdot \frac{4}{25} = \frac{4}{25}.
The question requests the product of all positive real values of xx satisfying the original equation.

Anahtar Kavram

Solving exponential equations with variable bases and radical powers
Soru 25Soru

If aa is a real number greater than 11 such that axax=2a^x - a^{-x} = 2, what is the value of the expression a3x+a3xa2x+a2x\frac{a^{3x} + a^{-3x}}{a^{2x} + a^{-2x}}?

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Cevap: 523\frac{5\sqrt{2}}{3}

Cevap

523\frac{5\sqrt{2}}{3}
Squaring the given relationship axax=2a^x - a^{-x} = 2 gives a2x2+a2x=4a^{2x} - 2 + a^{-2x} = 4, which simplifies to a2x+a2x=6a^{2x} + a^{-2x} = 6. Adding 4 to both sides gives (ax+ax)2=8(a^x + a^{-x})^2 = 8, so ax+ax=22a^x + a^{-x} = 2\sqrt{2}. By the sum of cubes identity, a3x+a3x=(ax+ax)(a2x+a2x1)=22(61)=102a^{3x} + a^{-3x} = (a^x + a^{-x})(a^{2x} + a^{-2x} - 1) = 2\sqrt{2}(6 - 1) = 10\sqrt{2}. Dividing 10210\sqrt{2} by 66 gives the simplified result 523\frac{5\sqrt{2}}{3}.

Adım Adım Çözüm

1
Square both sides of the given equation axax=2a^x - a^{-x} = 2.
(axax)2=a2x2(ax)(ax)+a2x=4    a2x+a2x=6(a^x - a^{-x})^2 = a^{2x} - 2(a^x)(a^{-x}) + a^{-2x} = 4 \implies a^{2x} + a^{-2x} = 6.
Expanding the binomial square allows us to find the denominator a2x+a2xa^{2x} + a^{-2x} directly.
2
Determine the value of ax+axa^x + a^{-x}.
(ax+ax)2=a2x+2+a2x=6+2=8    ax+ax=8=22(a^x + a^{-x})^2 = a^{2x} + 2 + a^{-2x} = 6 + 2 = 8 \implies a^x + a^{-x} = \sqrt{8} = 2\sqrt{2}.
Since a>1a > 1, ax>0a^x > 0 and ax>0a^{-x} > 0, their sum must be positive.
3
Use the sum of cubes identity u3+v3=(u+v)(u2uv+v2)u^3 + v^3 = (u + v)(u^2 - uv + v^2) to evaluate a3x+a3xa^{3x} + a^{-3x}.
a3x+a3x=(ax+ax)(a2x1+a2x)=(22)(61)=102a^{3x} + a^{-3x} = (a^x + a^{-x})(a^{2x} - 1 + a^{-2x}) = (2\sqrt{2})(6 - 1) = 10\sqrt{2}.
Factoring the numerator breaks it into terms whose numerical values are known.
4
Compute the ratio of numerator to denominator.
\frac{a^{3x} + a^{-3x}}{a^{2x} + a^{-2x}} = \frac{10\sqrt{2}}{6} = \frac{5\sqrt{2}}{3}.
Simplify the fraction by dividing numerator and denominator by 2.

Anahtar Kavram

Algebraic transformations of exponential expressions using polynomial identities.
Tahmini Süre:2m 30s
Soru 26Soru
If xx is a real number greater than 11 satisfying the exponential equation
(xx)x=x(xx)\left(x^x\right)^{\sqrt{x}} = x^{\left(x^{\sqrt{x}}\right)}
what is the value of xx?
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Cevap: 94\frac{9}{4}

Cevap

The value of xx is 94\frac{9}{4}.
Applying the exponent rule (ab)c=abc(a^b)^c = a^{bc} simplifies the left side to xxxx^{x\sqrt{x}}. Since the base x>1x > 1 is identical on both sides, we set the exponents equal: xx=xxx\sqrt{x} = x^{\sqrt{x}}. Expressing xxx\sqrt{x} as x3/2x^{3/2} yields x3/2=xxx^{3/2} = x^{\sqrt{x}}, which implies x=32\sqrt{x} = \frac{3}{2}. Squaring both sides gives x=94x = \frac{9}{4}.

Adım Adım Çözüm

1
Apply the power rule (ab)c=abc(a^b)^c = a^{bc} to the left-hand side of the equation.
(xx)x=xxx=xx3/2\left(x^x\right)^{\sqrt{x}} = x^{x \cdot \sqrt{x}} = x^{x^{3/2}}
Raising a power to another exponent requires multiplying the exponents: xx1/2=x1+1/2=x3/2x \cdot x^{1/2} = x^{1 + 1/2} = x^{3/2}.
2
Equate the exponents of the expressions on both sides, as the bases are equal and x>1x > 1.
xx=xxx \sqrt{x} = x^{\sqrt{x}}, which means x3/2=xxx^{3/2} = x^{\sqrt{x}}
If xA=xBx^A = x^B and x>1x > 1, then A=BA = B.
3
Equate exponents once more for the base xx.
32=x\frac{3}{2} = \sqrt{x}
Since the bases are identical (x>1x > 1), their exponents must be equal.
4
Square both sides to solve for xx.
x=(32)2=94x = \left(\frac{3}{2}\right)^2 = \frac{9}{4}
Squaring x\sqrt{x} isolates xx.

Anahtar Kavram

Properties of exponents and nested power rules with radicals
Tahmini Süre:2m 0s
Soru 27Soru
If xx is a positive real number satisfying the equation
x3xxx1/43=16\sqrt[3]{\frac{x^3 \sqrt{x\sqrt{x}}}{x^{-1/4}}} = 16
what is the value of xx?
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Cevap: 8

Cevap

8
By converting all radicals into fractional exponents and systematically applying exponent rules, the expression under the cube root simplifies to x4x^4. Taking the cube root gives x4/3=16x^{4/3} = 16. Solving for xx by raising both sides to 3/43/4 yields x=163/4=(24)3/4=23=8x = 16^{3/4} = (2^4)^{3/4} = 2^3 = 8.

Adım Adım Çözüm

1
Express the inner nested radical using fractional exponents
\sqrt{x\sqrt{x}} = \sqrt{x \cdot x^{1/2}} = \sqrt{x^{3/2}} = x^{3/4}
Applying the product and power rules of exponents: xaxb=xa+bx^a \cdot x^b = x^{a+b} and (xa)b=xab(x^a)^b = x^{ab}.
2
Simplify the numerator inside the outer radical
x^3 \cdot x^{3/4} = x^{3 + 3/4} = x^{15/4}
Multiplying exponential terms with the same base requires adding their exponents.
3
Divide by the negative exponent in the denominator
\frac{x^{15/4}}{x^{-1/4}} = x^{15/4 - (-1/4)} = x^{16/4} = x^4
Dividing exponential terms with the same base requires subtracting the denominator exponent from the numerator exponent.
4
Apply the outer cube root to the simplified expression
x43=(x4)1/3=x4/3\sqrt[3]{x^4} = (x^4)^{1/3} = x^{4/3}
The nn-th root of an expression is equivalent to raising that expression to the power of 1/n1/n.
5
Solve the resulting exponential equation for xx
x^{4/3} = 16 \implies x = 16^{3/4} = (2^4)^{3/4} = 2^3 = 8
Raise both sides of x4/3=16x^{4/3} = 16 to the power of 3/43/4 to isolate xx.

Anahtar Kavram

Simplifying nested algebraic radicals and solving equations with fractional exponents using exponent rules.
Soru 28Soru

If xx is a real number satisfying the radical equation x+7x=1\sqrt{x + 7} - x = 1, what is the value of xx?

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Cevap: 22

Cevap

The value of xx is 22.
Isolating the square root yields x+7=x+1\sqrt{x + 7} = x + 1. Squaring both sides produces x+7=x2+2x+1x + 7 = x^2 + 2x + 1, which reduces to the quadratic equation x2+x6=0x^2 + x - 6 = 0. Factoring yields (x+3)(x2)=0(x + 3)(x - 2) = 0, giving potential roots of x=3x = -3 and x=2x = 2. Testing x=2x = 2 in the original expression yields 2+72=32=1\sqrt{2+7} - 2 = 3 - 2 = 1, confirming it is correct.

Adım Adım Çözüm

1
Isolate the radical expression on one side of the equation.
x+7=x+1\sqrt{x + 7} = x + 1
Isolating the radical allows squaring both sides cleanly to eliminate the radical sign.
2
Square both sides of the equation.
x+7=(x+1)2=x2+2x+1x + 7 = (x + 1)^2 = x^2 + 2x + 1
Squaring removes the square root on the left side.
3
Rearrange into standard quadratic form ax2+bx+c=0ax^2 + bx + c = 0.
x2+x6=0x^2 + x - 6 = 0
Subtracting x+7x + 7 from both sides collects all terms on one side.
4
Factor the quadratic equation and solve for potential values of xx.
(x+3)(x2)=0    x=3 or x=2(x + 3)(x - 2) = 0 \implies x = -3 \text{ or } x = 2
Setting each factor to zero identifies potential solutions.
5
Substitute each potential solution back into the original equation x+7x=1\sqrt{x + 7} - x = 1 to check for extraneous roots.
For x=2x = 2: 2+72=32=1\sqrt{2 + 7} - 2 = 3 - 2 = 1 (Valid). For x=3x = -3: 3+7(3)=2+3=51\sqrt{-3 + 7} - (-3) = 2 + 3 = 5 \neq 1 (Extraneous).
Squaring an equation can introduce false solutions that must be eliminated.

Anahtar Kavram

Solving radical equations and checking for extraneous solutions
Tahmini Süre:1m 30s
Soru 29Soru

For all positive real numbers aa and bb, which of the following expressions are equivalent to (a2b3a4b2)1/2\left( \frac{a^{-2} b^3}{\sqrt{a^4 b^{-2}}} \right)^{-1/2}? Select all that apply.

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Cevap: a2b2\frac{a^2}{b^2}; (ba)2\left( \frac{b}{a} \right)^{-2}; a4b4\sqrt{\frac{a^4}{b^4}}

Cevap

The expressions equivalent to the given quantity are a2b2\frac{a^2}{b^2}, (ba)2\left( \frac{b}{a} \right)^{-2}, and a4b4\sqrt{\frac{a^4}{b^4}}.
Simplifying the original expression step-by-step yields a2b2\frac{a^2}{b^2}. The expressions a2b2\frac{a^2}{b^2}, (ba)2=(ab)2=a2b2\left( \frac{b}{a} \right)^{-2} = \left( \frac{a}{b} \right)^2 = \frac{a^2}{b^2}, and a4b4=a2b2\sqrt{\frac{a^4}{b^4}} = \frac{a^2}{b^2} are all identical to the simplified form.

Adım Adım Çözüm

1
Simplify the radical in the denominator of the inner expression.
Since a>0a > 0 and b>0b > 0, a4b2=a4b2=a2b1\sqrt{a^4 b^{-2}} = \sqrt{a^4} \cdot \sqrt{b^{-2}} = a^2 b^{-1}.
Applying the square root to each variable power individually.
2
Simplify the expression inside the outer parenthesis.
\frac{a^{-2} b^3}{a^2 b^{-1}} = a^{-2 - 2} b^{3 - (-1)} = a^{-4} b^4.
Subtracting exponents of like bases according to the quotient rule of exponents.
3
Apply the outer exponent of 12-\frac{1}{2}.
(a^{-4} b^4)^{-1/2} = (a^{-4})^{-1/2} (b^4)^{-1/2} = a^2 b^{-2} = \frac{a^2}{b^2}.
Multiplying internal exponents by 12-\frac{1}{2} according to the power rule of exponents.
4
Evaluate each choice against the simplified form a2b2\frac{a^2}{b^2}.
The expressions a2b2\frac{a^2}{b^2}, (ba)2\left(\frac{b}{a}\right)^{-2}, and a4b4\sqrt{\frac{a^4}{b^4}} are all algebraically equivalent to a2b2\frac{a^2}{b^2}.
Testing algebraic equivalence using standard exponent and radical laws.

Anahtar Kavram

Properties of exponents and radicals, including power of a quotient, quotient rule, negative exponents, and square roots of powers.
Tahmini Süre:1m 30s
Soru 30Soru

For all real numbers xx, what is the numerical value of the expression 3x+23x3x1+3x2\frac{3^{x+2} - 3^x}{3^{x-1} + 3^{x-2}}?

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Cevap: 18

Cevap

The numerical value of the expression is 18.
Factoring 3x3^x from both terms in the numerator gives 3x(321)=83x3^x(3^2 - 1) = 8 \cdot 3^x. Factoring 3x3^x from both terms in the denominator gives 3x(31+32)=3x(13+19)=493x3^x(3^{-1} + 3^{-2}) = 3^x\left(\frac{1}{3} + \frac{1}{9}\right) = \frac{4}{9} \cdot 3^x. Dividing the two expressions cancels 3x3^x entirely, resulting in 849=8×94=18\frac{8}{\frac{4}{9}} = 8 \times \frac{9}{4} = 18.

Adım Adım Çözüm

1
Factor out 3x3^x from the numerator.
3x+23x=3x(321)=3x(91)=83x3^{x+2} - 3^x = 3^x(3^2 - 1) = 3^x(9 - 1) = 8 \cdot 3^x
Applying the exponent rule am+n=amana^{m+n} = a^m \cdot a^n allows factoring out the common exponential factor 3x3^x.
2
Factor out 3x3^x from the denominator.
3x1+3x2=3x(31+32)=3x(13+19)=3x(49)3^{x-1} + 3^{x-2} = 3^x(3^{-1} + 3^{-2}) = 3^x\left(\frac{1}{3} + \frac{1}{9}\right) = 3^x\left(\frac{4}{9}\right)
Applying negative exponent rules an=1ana^{-n} = \frac{1}{a^n} allows evaluating the remaining numerical terms inside the parentheses.
3
Simplify the overall fraction by dividing the factored numerator by the factored denominator.
\frac{8 \cdot 3^x}{\frac{4}{9} \cdot 3^x} = \frac{8}{\frac{4}{9}} = 8 \times \frac{9}{4} = 18
The non-zero common term 3x3^x cancels from both numerator and denominator, leaving a constant integer.

Anahtar Kavram

Factoring and simplifying exponential expressions with variable exponents.
Soru 31Soru

If xx is a real number satisfying the exponential equation 9x+132x+1=1629^{x+1} - 3^{2x+1} = 162, what is the value of 4x4^x?

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Cevap: 8

Cevap

8
By converting 9x+19^{x+1} to 32x+23^{2x+2} and factoring out 32x3^{2x}, the equation simplifies to 632x=1626 \cdot 3^{2x} = 162. Dividing by 6 gives 32x=273^{2x} = 27, so 2x=32x = 3 and x=32x = \frac{3}{2}. Raising 4 to the power of 32\frac{3}{2} yields (4)3=8(\sqrt{4})^3 = 8.

Adım Adım Çözüm

1
Rewrite terms with a common base of 3.
9x+1=(32)x+1=32(x+1)=32x+29^{x+1} = (3^2)^{x+1} = 3^{2(x+1)} = 3^{2x+2}
Since 9 is a power of 3 (9=329 = 3^2), applying exponent rules converts the equation to base 3.
2
Factor out the common exponential expression 32x3^{2x}.
32x+232x+1=32x3232x31=32x(93)=632x3^{2x+2} - 3^{2x+1} = 3^{2x} \cdot 3^2 - 3^{2x} \cdot 3^1 = 3^{2x}(9 - 3) = 6 \cdot 3^{2x}
Using product rule of exponents (3a+b=3a3b3^{a+b} = 3^a \cdot 3^b) allows combining like terms.
3
Solve for xx.
632x=162    32x=27    32x=33    2x=3    x=326 \cdot 3^{2x} = 162 \implies 3^{2x} = 27 \implies 3^{2x} = 3^3 \implies 2x = 3 \implies x = \frac{3}{2}
Dividing both sides by 6 yields 32x=273^{2x} = 27, and equating exponents of matching bases gives x=32x = \frac{3}{2}.
4
Evaluate the target expression 4x4^x.
43/2=(41/2)3=23=84^{3/2} = (4^{1/2})^3 = 2^3 = 8
Substituting x=32x = \frac{3}{2} into 4x4^x means taking the square root of 4 and raising it to the third power.

Anahtar Kavram

Solving exponential equations using common bases and exponent properties
ÖncekiSayfa 2 / 2
Algebraic Exponents and Radicals Alıştırma Soruları — GRE General Test — Sayfa 2 | Examkin