Question 297145
{{{x^2+8x=9}}}
Take (1/2) the x coefficient, square it, add it to both sides.
{{{x^2+8x+16=9+16}}}
{{{(x+4)^2=25}}}
Take the sqaure root of both sides,
{{{x+4=0 +- 5}}}
{{{x=-4 +- 5}}}
{{{x=-9}}} and {{{x=-1}}}