Question

Equação 2 g.

A)x²-6x-7=0
B)8x²+3x=0
C)x²-x-12=5x-5
D)x²+7=7+2x
E)x²+4x=1=x²

Answer 1

A)x²-6x-7=0

x'=[6+√(36+28)]/2=(6+8)/2=7

x''=[6-√(36+28)]/2=(6-8)/2=-1

 B)8x²+3x=0

x(8x+3)=0

x=0

8x+3=0 ==>x=-3/8

 C)x²-x-12=5x-5

x²-6x-7=0

x'=[6+√(36+28)]/2=(6+8)/2=7

x''=[6-√(36+28)]/2=(6-8)/2=-2

 D)x²+7=7+2x

x²-2x=0

x*(x-2)=0

x=0

x-2=0 ==>x=2

 E)x²+4x=1=x²

deve ser x²+4x+1=x²

4x+1=0

x=-1/4