Question 855279
Use the FOIL method,
{{{(x+3)^2=(x+3)(x+3)}}}
First - {{{x(x)=x*2}}}
Outer - {{{x(3)=3x}}}
Inner - {{{3(x)=3x}}}
Last - {{{3(3)=9}}}
{{{(x+3)^2=x^2+3x+3x+9}}}
{{{(x+3)^2=x^2+6x+9}}}