Madeline was completing the square, and her work is shown below. Identify the line where she made her mistake. f (x) = 3x2 + 6x - 7 Line 1: f (x) = 3 (x2 + 2x) - 7 Line 2: f (x) = 3 (x2 + 2x + 1) - 7 - 1 Line 3: f (x) = 3 (x + 1) 2 - 8

In line two, Madlime added positive one in the bracket, but subtracted one outside of the bracket without considering the factor outside of the bracket. Therefore, line 2 should be f (x) = 3 (x2+2x+1-1) - 7

Line 3: f (x) = 3 (x+1) 2-7-3

Line 4: f (x) = 3 (x+1) 2-10