Question 436980
Rewrite the expression:{{{(3x)^2+2*3x*7 +7^2}}}, remember the formula:

{{{a^2+2ab+b^2=(a+b)^2}}}. In our exercise a=3x and b=7, therefore

{{{(3x)^2+2*3x*7+7^2=(3x+7)^2}}}.

Done.