Question

Difficulty: HardEvaluating Algebraic Expressions

If p=−3p = -3, q=−12q = -\frac{1}{2}, and r=8r = 8, what is the value of the algebraic expression below?

p2q−3−r4/3(pq−12)2−r1/3\frac{p^2 q^{-3} - r^{4/3}}{\left(pq - \frac{1}{2}\right)^2 - r^{1/3}}
Answer:The value of the expression is 【88】.

Answer

88
Evaluating each component using exponent rules and standard order of operations yields −72−16=−88-72 - 16 = -88 in the numerator and 1−2=−11 - 2 = -1 in the denominator. Dividing −88-88 by −1-1 results in the final value of 8888.

Step-by-Step Solution

1
Evaluate the terms in the numerator containing negative and rational exponents.
p2q−3=(−3)2(−12)−3=9⋅(−8)=−72p^2 q^{-3} = (-3)^2 \left(-\frac{1}{2}\right)^{-3} = 9 \cdot (-8) = -72 and r4/3=84/3=(81/3)4=24=16r^{4/3} = 8^{4/3} = (8^{1/3})^4 = 2^4 = 16.
Apply exponent rules for negative bases with integer and fractional powers: a−n=1ana^{-n} = \frac{1}{a^n} and am/n=(an)ma^{m/n} = (\sqrt[n]{a})^m.
2
Subtract the evaluated terms to determine the total numerator value.
\text{Numerator} = -72 - 16 = -88.
Combine the evaluated terms according to the numerator expression p2q−3−r4/3p^2 q^{-3} - r^{4/3}.
3
Evaluate the grouped and exponential terms in the denominator.
pq−12=(−3)(−12)−12=32−12=1pq - \frac{1}{2} = (-3)\left(-\frac{1}{2}\right) - \frac{1}{2} = \frac{3}{2} - \frac{1}{2} = 1. Then (pq−12)2=12=1\left(pq - \frac{1}{2}\right)^2 = 1^2 = 1, and r1/3=81/3=2r^{1/3} = 8^{1/3} = 2.
Follow the order of operations by simplifying inside the parentheses first, then applying the exponent.
4
Calculate the denominator and divide the numerator by the denominator.
\text{Denominator} = 1 - 2 = -1 .Dividingthenumeratorbythedenominatorgives. Dividing the numerator by the denominator gives \frac{-88}{-1} = 88$.
Perform the final subtraction in the denominator and divide to simplify the fraction fully.

Key Concept

Evaluating Algebraic Expressions with Negative and Fractional Exponents
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