Slove x^2-8x=20 by completing the square. which is the solution set of equation?

x^2-8x=20

Move + 20 to the other side. Sign changes from + 20 to - 20

x^2-8x-20=20-20

x^2-8x-20=0

Think about two numbers that equals to - 20 and - 8.

(x-10) (x+2) = 0

x-10=0 (move - 10 to the other side). Sign changes from - 10 to 10

x-10+10=0+10

x=10

x+2=0 (move + 2 to the other side). Sign changes from + 2 to - 2

x+2-2=0-2

x=-2

Answer:

x=10, x=-2