Question

Remove the parentheses and simplify 3a^2-6ab+3b^2-5(-6a^2+7ab-7b^2) 

Answer 1

$3a^2-6ab+3b^2-5(-6a^2+7ab-7b^2)=\\\\3a^2-6ab+3b^2+30a^2-35ab+35b^2=\\\\33a^2-41ab+38b^2$