Question

sendo A=x+5, B=x-3, C= X-7 e D=x+3, determine:
a) A+B
B) A.B
C) A.C
D) A.D
E) B.C
F) C.D

Answer 1

a) (x+5)+(x-3)
2x+2
2x=-2
x-2/2
x=-1

b) (x+5).(x-3)
x²-3x+5x-15
x²+2x-15=0
A=1
B=2
C= -15
Δ= 2²-4.1.(-15)
Δ=64

X=-2+/-√Δ
        2.1
X1 =-2+8/2= 3
X2= -2-8/2= -5

c)(x+5).(x-7)
x²-7x+5x-35
x²-2x-35=0
A=1
B=-2
C=-35
(Repete o procedimento de cima, usando a fórmula de Baskara)
X1= 7
X2= -5

d)(x+5).(x+3)
x²+3x+5x+15
x²+8x+15=0
X1=-2
X2=-3

e)(x-3).(x-7)
x²-7x-3x+21
x²-10x+21=0
X1=7
X2=3

f)(x-7).(x+3)
x²+3x-7x-21
x²-4x-21=0
X1=7
X2=-3

Answer 2

a) (x+5)+(x-3)
2x+2
2x=-2
x-2/2
x=-1

b) (x+5).(x-3)
x²-3x+5x-15
x²+2x-15=0
A=1
B=2
C= -15
Δ= 2²-4.1.(-15)
Δ=64

X=-2+/-√Δ
        2.1
X1 =-2+8/2= 3
X2= -2-8/2= -5

c)(x+5).(x-7)
x²-7x+5x-35
x²-2x-35=0
A=1
B=-2
C=-35
X1= 7
X2= -5

d)(x+5).(x+3)
x²+3x+5x+15
x²+8x+15=0
X1=-2
X2=-3

e)(x-3).(x-7)
x²-7x-3x+21
x²-10x+21=0
X1=7
X2=3

f)(x-7).(x+3)
x²+3x-7x-21
x²-4x-21=0
X1=7
X2=-3