Question

resolva x ao quadrado - 7x = 0

Answer 1

$x^{2} -7x=0\\\\\\ por.evidencia:\\\\ x(x-7)=0\\\\\\ x=0\\\\ x-7=0\to x=7\\\\\\ S=(0;7)$

Answer 2

$x^2-7x=0\\x(x-7)=0\\\boxed{x'=0} \\\\ou\\\\x''-7=0\\\boxed{x''=7}\\\\Observe:\\\\x'=0\\0(x-7)=0\\0=0\\\\x''=7\\\\x(7-7)=0\\x.0=0\\0=0$