Question

Calcular a equação:
x(x-4) = x-4

Answer 1

x*2-4x=x-4
x*2-5x+4=0
Faz bhaskara e x1=-4 x2=-1

Answer 2

$x(x-4) = x-4\to\\\\ x^{2} -4x-x+4=0\to \\\\ x^{2} -5x+4=0\\\\ a=1;b=-5;c=4\\\\\\ \Delta=b^2-4ac\to \Delta=(-5)^2-4*1*4\to \Delta=25-16\to \Delta=9\\\\x' \neq x''\\\\\\ x= \frac{-b\pm \sqrt{\Delta} }{2a} \to x= \frac{-(-5)\pm \sqrt{9} }{2*1} \to x= \frac{5\pm3 }{2} \to \\\\\\ x'= \frac{5+3 }{2} \to x'= \frac{8}{2} \to x'=4\\\\\\ x''= \frac{5-3 }{2} \to x''= \frac{2 }{2} \to x''=1\\\\\\\\ S=\{1;4\}$