Question

como fazer essa equação do 2 grau ?×2-4×=0?

Answer 1

$x^{2} -4x=0\\\\\\ Por~~Evid\^encia:\\\\\\ x(x-4)=0\\\\\\ \boxed{x=0}\\ \\x-4=0\to~~\boxed{x=4}\\\\\\\\ \large\boxed{\boxed{S=\{0~;~4\}}}$