Question

Resolva as equações:
a) x²-7x-8=0
b) x²+10x-11=0
c) 2x²-5x-5=0
d) -5x²+2x+7=0
(com calculo)
Alguém por favor!!

Answer 1

a) Δ=b^2 -4ac   Δ= 49-4.1.(-8) Δ=81
x1 e x2= -b+√Δ/2a    x1= 7+9/2a   x1= 16/2   x1= 8   x2= 7-9/2   x2= -1

b) x²+10x-11=0
Δ=b^2 -4ac Δ= 100 -4.1.(-11)  Δ= 36  x1 e x2= -b+√Δ/2a  x1= -10+6/2 x1=2  x2= -10-6/2    x2 = -8

c) 2x²-5x-5=0
Δ=b^2 -4ac  Δ=25 -4.2.(-5)  Δ= 25+40 Δ=65
 x1 e x2= -b+√Δ/2a
x1= 5+√65/4  x1= 5+8/4  x1= 13/4  x1= 3,25
x2= 5-√65/4  x2= 5-8/4   x2= -3/4


d) -5x²+2x+7=0

Δ=b^2 -4ac Δ=4 -4.-5.7   Δ= 4+140  Δ= 144
x1 e x2= -b+√Δ/2a   x1= -2+12/2.(-5)   x1= -10/-10   x1= 1
x2= -b+√Δ/2a   x1= -2-12/2.(-5)   x1= -14/-10   x