Question

Difficulty: HardOperations with Variable Exponents
Assume xx and yy are non-zero real numbers. When the algebraic expression (2x−3y4)34x5y−2\frac{(2x^{-3}y^4)^3}{4x^5y^{-2}} is fully simplified to the form cxaybcx^ay^b, what is the integer value of bb?

Answer: 14

Answer

14
The expression simplifies to 2x−14y142x^{-14}y^{14}. Because the question asks for the exponent of yy, which is denoted by bb in the target expression cxaybcx^ay^b, the correct value is 14.

Step-by-Step Solution

1
Apply the power of a product rule to the numerator.
(2x−3y4)3=23(x−3)3(y4)3=8x−9y12(2x^{-3}y^4)^3 = 2^3(x^{-3})^3(y^4)^3 = 8x^{-9}y^{12}
When an algebraic term with coefficients and variables is raised to a power, the outer exponent must be distributed to each individual factor inside the parentheses.
2
Set up the division by applying the quotient rule for each base.
8x−9y124x5y−2=(84)⋅(x−9x5)⋅(y12y−2)\frac{8x^{-9}y^{12}}{4x^5y^{-2}} = \left(\frac{8}{4}\right) \cdot \left(\frac{x^{-9}}{x^5}\right) \cdot \left(\frac{y^{12}}{y^{-2}}\right)
Separating the expression by identical bases allows the independent application of the quotient rule for exponents.
3
Evaluate the exponent for the yy term to find the value of bb.
y12÷y−2=y12−(−2)=y12+2=y14y^{12} \div y^{-2} = y^{12 - (-2)} = y^{12 + 2} = y^{14}
When dividing exponential terms with the same base, subtract the denominator's exponent from the numerator's exponent. Care must be taken with the double negative.
4
Identify the requested integer value.
b=14b = 14
The question specifically asks for the integer value of bb in the final simplified form cxaybcx^ay^b, which represents the exponent of the yy term.

Key Concept

Applying the power of a power and quotient of powers rules for variable exponents.
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