Question

Difficulty: MediumProperties of Exponents in Algebraic Expressions

For all positive real numbers ww, the expression (w4ww1.5)2/3\left(\frac{w^4 \cdot \sqrt{w}}{w^{-1.5}}\right)^{2/3} is equivalent to wkw^k, where kk is a constant. What is the value of kk?

Answer: 4

Answer

The value of kk is 44.
Applying the exponent rules in sequence: first, rewrite the square root as a fractional exponent to get w0.5w^{0.5}. Next, multiply the terms in the numerator by adding their exponents: 4+0.5=4.54 + 0.5 = 4.5. Then, divide the numerator by the denominator by subtracting the denominator's exponent from the numerator's exponent: 4.5(1.5)=64.5 - (-1.5) = 6. Finally, raise this result to the 2/32/3 power by multiplying the exponents: 6×(2/3)=46 \times (2/3) = 4. This yields w4w^4, so the constant exponent is 44.

Step-by-Step Solution

1
Convert the radical expression to an exponential expression.
w=w0.5\sqrt{w} = w^{0.5}
Converting all terms to base ww with decimal or fractional exponents makes it easier to apply exponent properties.
2
Apply the product rule of exponents to the numerator.
w4w0.5=w4+0.5=w4.5w^4 \cdot w^{0.5} = w^{4 + 0.5} = w^{4.5}
When multiplying exponential terms with the same base, add their exponents: wawb=wa+bw^a \cdot w^b = w^{a+b}.
3
Apply the quotient rule of exponents to the fraction.
w4.5w1.5=w4.5(1.5)=w6\frac{w^{4.5}}{w^{-1.5}} = w^{4.5 - (-1.5)} = w^6
When dividing exponential terms with the same base, subtract the exponent of the denominator from the exponent of the numerator: wawb=wab\frac{w^a}{w^b} = w^{a-b}.
4
Apply the power rule of exponents to the simplified term.
(w6)2/3=w623=w4(w^6)^{2/3} = w^{6 \cdot \frac{2}{3}} = w^4
When raising a power to another power, multiply the exponents: (wa)b=wab(w^a)^b = w^{a \cdot b}.

Key Concept

Properties of Exponents in Algebraic Expressions
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