Question

Difficulty: MediumEvaluating Algebraic Expressions

If u=−3u = -3 and v=−12v = -\frac{1}{2}, what is the value of the algebraic expression below? Enter your numerical answer in the blank.

Answer:The value of the expression 4uv2−u22v−u\frac{4uv^2 - u^2}{2v - u} is 【-6】.

Answer

The value of the expression when evaluated at u=−3u = -3 and v=−12v = -\frac{1}{2} is −6-6.
Substituting u=−3u = -3 and v=−12v = -\frac{1}{2} into the numerator gives 4(−3)(−12)2−(−3)2=−3−9=−124(-3)(-\frac{1}{2})^2 - (-3)^2 = -3 - 9 = -12. Substituting into the denominator gives 2(−12)−(−3)=−1+3=22(-\frac{1}{2}) - (-3) = -1 + 3 = 2. Dividing −12-12 by 22 results in −6-6.

Step-by-Step Solution

1
Evaluate the terms containing exponents in the numerator.
v2=(−12)2=14v^2 = \left(-\frac{1}{2}\right)^2 = \frac{1}{4} and u2=(−3)2=9u^2 = (-3)^2 = 9.
Exponents must be calculated before multiplication according to the order of operations.
2
Evaluate the numerator 4uv2−u24uv^2 - u^2.
4(−3)(14)−9=−3−9=−124(-3)\left(\frac{1}{4}\right) - 9 = -3 - 9 = -12.
Multiply 4×(−3)×144 \times (-3) \times \frac{1}{4} to get −3-3, then subtract 99.
3
Evaluate the denominator 2v−u2v - u.
2(−12)−(−3)=−1+3=22\left(-\frac{1}{2}\right) - (-3) = -1 + 3 = 2.
Multiplying 22 by −12-\frac{1}{2} gives −1-1, and subtracting negative 33 is equivalent to adding 33.
4
Divide the numerator by the denominator.
−122=−6\frac{-12}{2} = -6.
Dividing −12-12 by 22 yields the final result −6-6.

Key Concept

Evaluating algebraic expressions involving negative numbers, fractions, and order of operations.
Estimated Time:1m 30s
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