Answer:
Steps in rewriting :
y = 3 x² + 9 x - 18 = 3 ( x² + 3 x ) - 18 = 3 (( x² + 3 x + 9/4 ) - 9/4) - 18 =
= 3 ( x + 3/2 )² - 27/4 - 18 = 3 ( x + 3/2 )² - 99/4
Answer:
3 must be factored from 3 x² + 9 x.
Source: https://brainly.com/question/1531931