group x terms 0=(x^2-6x)-11 take 1/2 of linear coefient (-6) and square it -6/2=-3, (-3)^2=9 add positive and neative to inside of parenthasees 0=(x^2-6x+9-9)-11 complete square 0=((x-3)^2-9)-11 expand 0=(x-3)^2-9-11 0=(x-3)^2-20 add 20 to both sides 20=(x-3)^2 sqrt both sides remember positive and negative roots
