Question

-x²+13x-40=0

x²-9=0

x²+3x=0

Answer 1

Olá!

a)por Bhaskara 

-x²+13x-40=0

Δ=b²-4.a.c
Δ=13²-4.(-1).40
Δ=169-160=
Δ=9

x=-b+-√Δ\2.a

x'=-13+3\2.(-1)=-10\-2=5

x''=-13-3\-2=-16\-2=8

b)x²-9=0

x²=9
x=√9
x=+3 ou -3

c)x²+3x=0

fatoração:

x(x+3)=0

x=0
x-3=0
x=3

s=3 e 0