Question

 equações de 2 grau x² + 5x = 0

Answer 1

Coloque o x em evidência:
x²+5x=0
x (x+5)=0
x=0 ;  x+5=0
          x=-5

S={-5 , 0}

Answer 2

$Delta= b^{2} -4ac\\Delta= 5^{2} -4*1*0\\Delta=25-0\\Delta=25\\\\x=\frac{-b\pm \sqrt{Delta} }{2a}\\\\x= \frac{-5\pm \sqrt{25}}{2}\\\\x= \frac{-5\pm5}{2}\\\\x=-5\\ou\\x=0$