## anonymous one year ago 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 Line 1 Line 2 Line 3 She did not make any mistakes

1. anonymous

$3{x}^{2}+6x-7$ fits the formula a{x}^{2}+bx+c, where a = 3, b = 6 and c = -7. Use the complete the square formula. ${a(x+D)}^{2}+E$ $D=\frac{b}{2a}$ Also, find E. $E=c-\frac{{b}^{2}}{4a}$ Plug in D and E in ${a(x+D)}^{2}+E$ to receive your answer. Hint: so Madeline got E wrong.

2. anonymous

Thanks

3. precal

Line two is wrong Madeline needs to -3(1)