Question 273318
{{{ (x+4)(x-9)=4x}}}
{{{x^2 + 4x - 9x - 36 - 4x = 0}}}
{{{x^2 - 9x - 36 = 0}}}
Completing the square:
{{{x^2 - 9x + (9/2)^2 = (9/2)^2 + 36}}}
{{{x^2 - 9x + 81/4 = 81/4 + 144/4}}}
{{{(x - (9/2))^2 = 225/4}}}
{{{x - 9/2 = 15/2}}}
{{{x = 12}}}
and
{{{x - 9/2 = -15/2}}}
{{{x = -3}}}
the solutions are {{{x = 12}}} and {{{x = -3}}}
check:
{{{ (x+4)(x-9)=4x}}}
{{{(12+4)(12-9) = 4*12}}}
{{{16*3 = 48}}}
{{{48 = 48}}}
and
{{{(-3+4)(-3-9) = 4*(-3)}}}
{{{1*(-12) = -12}}}
{{{-12 = -12}}}
OK