Question 65331
{{{3x*x = A}}}
{{{3x^2 = A}}}
{{{(3x - 2)(x - 2) = A - 36}}}
{{{3x^2 - 8x + 4 = A - 36}}}
substitute A for {{{3x^2}}}
{{{A - 8x + 4 = A - 36}}}
subtract A from both sides
{{{-8x + 4 = -36}}}
{{{8x = 36 + 4}}}
{{{8x = 40}}}
{{{x = 5}}}
{{{A = 3*5^2}}}
{{{A = 75}}} cm2 answer
check
{{{(3x - 2)(x - 2) = A - 36}}}
{{{(3*5 - 2)(5 - 2) = A - 36}}}
{{{13*3 = A - 36}}}
{{{A = 39 + 36}}}
{{{A = 75}}}
OK