-2(x - 1)^2 + 8 - Math Central

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Question from kasondra, a student:

y=-2(x-1)2[thats a square] +8 that need to be put in standard form
the answer is y= -2x2 -4x + 6
i got y= -2x2 -4x -4
i just dont get how my teacher got that answer

Hi Kasonra

(x - 1)² = x² - 2x + 1

-2(x - 1)² = -2(x² - 2x + 1) = -2x² + 4x -2

and hence

-2(x - 1)² + 8 = -2x² + 4x - 2 + 8 = -2x² + 4x + 6

Penny

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