Question

Difficulty: MediumEvaluating Algebraic Expressions

If x=3x = -3 and y=2y = 2, what is the value of the algebraic expression x2y(xy)22x+y2\frac{x^2 y - (x - y)^2}{2x + y^2}?

  1. A
    172-\frac{17}{2}
  2. B
    132-\frac{13}{2}
  3. C
    710\frac{7}{10}
  4. 72\frac{7}{2}Answer
  5. E
    432\frac{43}{2}

Answer

72\frac{7}{2}
Substituting x=3x = -3 and y=2y = 2 gives a numerator of (3)2(2)(32)2=1825=7(-3)^2(2) - (-3 - 2)^2 = 18 - 25 = -7 and a denominator of 2(3)+22=6+4=22(-3) + 2^2 = -6 + 4 = -2. Dividing 7-7 by 2-2 gives 72\frac{7}{2}.

Step-by-Step Solution

1
Evaluate the terms in the numerator
x2y=(3)2(2)=92=18x^2 y = (-3)^2(2) = 9 \cdot 2 = 18 and (xy)2=(32)2=(5)2=25(x - y)^2 = (-3 - 2)^2 = (-5)^2 = 25
Apply order of operations by performing parenthetical subtraction before squaring negative numbers.
2
Subtract the terms to find the total numerator value
1825=718 - 25 = -7
Subtract the squared binomial result from the first product.
3
Evaluate the denominator
2x+y2=2(3)+22=6+4=22x + y^2 = 2(-3) + 2^2 = -6 + 4 = -2
Multiply and square the variable values before adding.
4
Divide the numerator by the denominator and simplify
72=72\frac{-7}{-2} = \frac{7}{2}
Dividing a negative number by a negative number yields a positive result.

Key Concept

Evaluating Algebraic Expressions with Negative Bases and Parentheses
Estimated Time:1m 0s
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