Question

Katie solved the equation by completing the square.

Answer 1

Katie has equation $x^2+12x-7=0$ and wants to solve it completing the perfect square. In order to do it, first rewrite 7 in right side:

$x^2+12x=7.$

Then note that $12x=2\cdot 6\cdot x,$ so Katie has to add $6^2=36$ to both sides (because $x^2+12x+36=x^2+2\cdot 6\cdot x+6^2=(x+6)^2$):

 $x^2+12x+36=7+36,\\ \\(x+6)^2=43.$

Answer: correct choice is C.