Question 88704
{{{x^2=400}}}


{{{x^2-400=0}}} subtract 400 from both sides



*[invoke change_this_name4450 1, 0, -400]



{{{(x-20)(x+20)=0}}}


{{{x-20=0}}} or {{{x+20=0}}} Set each factor equal to zero


{{{x=20}}} or {{{x=-20}}} Solve for x