Question

X (ao quadrado) + 9x = 0

Answer 1

x²+9x= 0

Δ= b²-4.a.c
Δ= 81

x= -b+/-√Δ/2.a

x= -9+9/2= 0

x= -18/2= -9

Solução: {0 e -9}

Beleza?

Answer 2

x² + 9x = 0

x • (x + 9) = 0

x= 0

x + 9 = 0

x= - 9

S= ( 0 , - 9)