Question

What is the first step when rewriting y = 3x2 + 9x – 18 in the form y = a(x – h)2 + k?
3 must be factored from 3x2 + 9x
x must be factored from 3x2 + 9x
9 must be factored from 9x – 18
3 must be factored from 3x2 – 18

Answer 1

"3 must be factored from 3x2 + 9x."

Reason: factor the leading coefficient from the x^2 and x terms before completing the square:
y = 3x^2 + 9x − 18 = 3(x^2 + 3x) − 18.