Madeline was completing the square and her work is shown below. Identify the line where she made her mistake.

f(x) = 3x^2 + 6x − 7
Line 1: f(x) = 3(x + 2x) − 7
Line 2: f(x) = 3(x + 2x + 1) − 7 − 1
Line 3: f(x) = 3(x + 1)2 − 8

Question

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

anonymous · Answer

Where did the ^2 go?

anonymous · Answer

f(x) = 3x^2 + 6x − 7
Line 1: f(x) = 3(x + 2x) − 7
Line 2: f(x) = 3(x + 2x + 1) − 7 − 1
Line 3: f(x) = 3(x + 1)^2 − 8

anonymous · Answer

the ^2 on the second line is missing
should be 3(x^2+2x)-7

anonymous · Answer

well in line two should she have subtracted one on the end? I assume the ^2 is in every line

anonymous · Answer

she sould have subtracted 3

anonymous · Answer

yep!!

anonymous · Answer

assuming he messed up ^2 
the answer is line 2