SOLUTION: 2. Use completing the square to rewrite the following equation in transformational form: y = x2 + 8x - 12 A. y = (x-4)2 - 28 B. y = (x+4)2 - 28 C. y = (x+4)2 + 4 D

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: 2. Use completing the square to rewrite the following equation in transformational form: y = x2 + 8x - 12 A. y = (x-4)2 - 28 B. y = (x+4)2 - 28 C. y = (x+4)2 + 4 D      Log On


   

Question 1021870: 2. Use completing the square to rewrite the following equation in transformational form:
y = x2 + 8x - 12

A. y = (x-4)2 - 28
B. y = (x+4)2 - 28
C. y = (x+4)2 + 4
D. y = (x-4)2 + 4

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

y+=+x%5E2+%2B+8x+-+12+
y+=+%28x%5E2+%2B+8x%2Bb%5E2%29-b%5E2+-+12+-> compare %28x%5E2+%2B+8x%2Bb%5E2%29 with %28a%2Bb%29%5E2=a%5E2%2B2ab%2Bb%5E2 and you see a=1 and 2ab=8; so, we can find b
2ab=8->2%2A1%2Ab=8->b=4
y+=+%28x%5E2+%2B+8x%2B4%5E2%29-4%5E2+-+12+
y+=+%28x%2B4%29%5E2-16+-+12+
y+=+%28x%2B4%29%5E2-28+
so, answer is:
B. y+=+%28x%2B4%29%5E2+-+28+