Question 933999

{{{x^2+8x-15}}}

{{{(x^2+8x+___)-___-15}}}...complete square

{{{(x^2+8x+4^2)-4^2-15}}}

{{{(x+4)^2-16-15}}}

{{{(x+4)^2-31}}}

{{{(x+4)(x+4)-31}}}