Express 2x^2-4x-16 in the form a(x+h)^2+k, where a,h,k are real numbers.

Answer 1

hmmm, maybe complete the square ?
2 x^2 - 4 x - 16 = y
x^2 - 2 x - 8 = y/2
x^2 - 2 x = y/2 + 8
x^2 - 2 x + 1 = y/2 + 9
(x+1)^2 = y/2 + 9
2 (x+1)^2 - 18 = y , done

Answer 2

gotta watch those +/- signs
y = 2x^2-4x-16
y = 2(x^2-2x+1) - 18
y = 2(x-1)^2 - 18

Answer 3

whoops sorry !