Question

Determine o valor de × das seguintes exfassoes
A) (×+1).(×+2)-×=5
B) 4(2×+5)=100
C) 3 (5×-1)=81
D) (52+8). (×+1)=320
E) 4×-2=18
F) 60×+16=28

Answer 1

a) (x+1).(x+2)-x=5
x² +2x +x +2 -x = 5
x² +2x +2 = 5
x² +2x -3 = 0
Δ = 2² -4*1*(-3)
Δ = 4+12 = 16
x1 = (-2 + √16)/2*1
x1 = (-2+4)/2
x1 = 2/2 = 1

x2 = (-2 - √16)/2*1
x2 = (-2 -4)/2
x2 = -6/2 = -3

S = {-3,1}

b) 4(2x+5)=100 
8x +20=100
8x = 100-20
8x = 80
x = 80/8
x = 10

c) 3(5x-1)=81
15x -3 = 81
15x = 81+3
15x = 84
x = 84/15 = 28/5

d) (52+8). (x+1)=320
60(x+1) = 320
60x+60 = 320
60x = 320-60
60x = 260
x = 260/60
x = 26/6 = 13/3

e) 4x-2 = 18
4x = 18+2
4x = 20
x = 20/4
x = 5

f) 60x +16 = 28
60x = 28-16
60x = 12
x = 12/60 = 1/5

Espero ter ajudado ;) Abraços