Question

Difficulty: MediumProperties of Exponents in Algebraic Expressions

If the expression (x2y3)4(x−1y2)3\frac{(x^2 y^3)^4}{(x^{-1} y^2)^3} is written in the equivalent form xaybx^a y^b, what is the value of a−ba - b?

Answer: 5

Answer

5
Simplifying the numerator yields x8y12x^8 y^{12} and simplifying the denominator yields x−3y6x^{-3} y^6. Dividing these expressions by subtracting the exponents of like bases results in x8−(−3)y12−6=x11y6x^{8 - (-3)} y^{12 - 6} = x^{11} y^6. Comparing this to the expression xaybx^a y^b shows that a=11a = 11 and b=6b = 6. The value of a−ba - b is 11−6=511 - 6 = 5.

Step-by-Step Solution

1
Simplify the numerator of the expression.
x8y12x^8 y^{12}
Apply the power of a power and power of a product properties of exponents: (x2y3)4=x2⋅4y3⋅4(x^2 y^3)^4 = x^{2 \cdot 4} y^{3 \cdot 4}.
2
Simplify the denominator of the expression.
x−3y6x^{-3} y^6
Apply the power of a power and power of a product properties of exponents: (x−1y2)3=x−1⋅3y2⋅3(x^{-1} y^2)^3 = x^{-1 \cdot 3} y^{2 \cdot 3}.
3
Simplify the quotient by dividing the simplified numerator by the simplified denominator.
x11y6x^{11} y^6
Use the quotient property of exponents, xmxn=xm−n\frac{x^m}{x^n} = x^{m-n}, to subtract the exponents: 8−(−3)=118 - (-3) = 11 and 12−6=612 - 6 = 6.
4
Identify the values of aa and bb and compute the difference a−ba - b.
5
By comparing x11y6x^{11} y^6 to the target form xaybx^a y^b, we find a=11a = 11 and b=6b = 6. Subtracting bb from aa yields 11−6=511 - 6 = 5.

Key Concept

Properties of exponents including power of a power, power of a product, and quotient rules.
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