Question

The first three steps for solving the quadratic equation 8x^2+80x=-5 by completing the square are shown. Fill in the missing number in the last step

8x^2+80x=-5
8(x^2+10x)=-5
8(x^2+10x+25)=-5+ ?
A)-200
B)-25
C)25
D)200

Answer 1

D)200. Step 3 added 25 within the parentheses, and everything inside the parentheses is multiplied by 8. So, to keep the equation true, or balanced, you must add the same amount, 8 * 25, to the other side.