Question

Difficulty: EasyProperties of Exponents in Algebraic Expressions

The algebraic expression (x2)ax4\frac{(x^2)^a}{x^{-4}} is equivalent to x10x^{10} for all non-zero real numbers xx. What is the value of aa?

Answer: 3

Answer

The correct answer is 3.
The correct value for aa is 33. Applying the power of a power rule to (x2)a(x^2)^a yields x2ax^{2a}. Then, applying the quotient rule to x2ax4\frac{x^{2a}}{x^{-4}} yields x2a(4)=x2a+4x^{2a - (-4)} = x^{2a+4}. Equating the exponents gives 2a+4=102a + 4 = 10, which solves to a=3a = 3.

Step-by-Step Solution

1
Apply the power of a power property to the numerator.
(x2)a=x2a(x^2)^a = x^{2a}
When raising a power to another power, multiply the exponents: (xm)n=xmn(x^m)^n = x^{mn}.
2
Apply the quotient property of exponents to simplify the fraction.
x2ax4=x2a(4)=x2a+4\frac{x^{2a}}{x^{-4}} = x^{2a - (-4)} = x^{2a + 4}
When dividing exponential expressions with the same base, subtract the exponent in the denominator from the exponent in the numerator: xmxn=xmn\frac{x^m}{x^n} = x^{m-n}.
3
Set the resulting exponent equal to the exponent of the equivalent expression and solve for aa.
2a+4=10    2a=6    a=32a + 4 = 10 \implies 2a = 6 \implies a = 3
Since the bases are identical and the expressions are equivalent, their exponents must be equal.

Key Concept

Properties of Exponents in Algebraic Expressions
Rate this question