x^2+20x+100=36
-subtract 100 and move to other side
x^2+20x____=36-100
-divide 20 by 2 which gives you 10.
-square 10= (10)^2 which gives you 100.
-add the 100 to the right side of the equation.
(x+10)^2 = 36-100+100
(x+10)^2=36
-cancel out the square root and square root 36
(x+10)= 6
-subtract 10
x=-4
*Plug in (-4) into the equation to check your work*
