Respostas
01.
a) x + 6 = 10
x = 10 - 6 = 4
b) x - 7 = 3
x = 3 + 7 = 10
c) 2x +5 = 15
2x = 15 - 5
2x = 10
x = 10 /2 = 5
d) 5x - 9 = 11
5x = 11 + 9
5x = 20
x = 20/5 = 4
e) 2x + 2 = 20
2x = 20 - 2
2x = 18
x = 18/2 = 9
f) 3x - 7 = 2x + 2
3x -2x = 2 +7
x = 9
g) 3x +6 = -3x + 12
3x + 3x = 12 - 6
6x = 6
x = 6/6 = 1
h) 4a +7 = 2a +13
4a -2a = 13 -7
2a = 6
a = 6/2 = 3
i) 5r -3 = -r +15
5r + r = 15 +3
6r = 18
r = 18/6 = 3
j) x-4 = -3x +20
x + 3x = 20 +4
4x = 24
x = 24/4 = 6
k) 5.(x-2) = 3.(x-2)
5x - 10 = 3x - 6
5x -3x = -6 +10
2x = 4
x = 4/2 = 2
l) 2.(b-3) = b -2
2b -6 = b -2
2b -b = -2 +6
b = 4
m) 3.(x + 4) = 2.(x + 10)
3x +12 = 2x +20
3x - 2x = 20 - 12
x = 8
n) 4.(x-1) = 2.(x+4)
4x -4 = 2x +8
4x -2x = 8 + 4
2x = 12
x = 12/2 = 6
o) 5.(x+2) = 3.(x+5)
5x + 10 = 3x +15
5x -3x = 15 - 10
2x = 5
x = 5/2
02.
a) x + 10 = 12
x = 12 - 10
x = 2
b) 2x -5 = x +3
2x - x = 3 +5
x = 8
c) x + 8 = 12
x = 12 - 8
x = 4
d) 2x + 2(2x +2) = 28
2x + 4x + 4 = 28
6x = 28 -4
6x = 24
x = 24/6
x = 4
Largura = 2x = 2.4 = 8m
Comprimento = 4x + 4 = 4.4 +4 = 20m