Question

Como resolver a essas equaçoes?
a) x + 5 = 18
b) 2x + x = 7 -10x
c) x + 12 = - 2x - 9
d) 3·(x-7) = 5x
e) 17x - 7x = x + 18
f)9x + 9 + 3x = 15
g) x + 2x + 3 - 5x = 4x - 9

Answer 1

a) x + 5 = 18
x = 18 - 5
x = 13

S[13]


b) 2x + x = 7 -10x
2x + x + 10x = 7
13x = 7
x = 7/13

S[7/13]


c) x + 12 = - 2x - 9
x + 2x = - 9 - 12
3x = - 21
x = - 21/3
x = - 7

S[- 7]


d) 3·(x-7) = 5x
3x - 21 = 5x
3x - 5x = +21
- 2x = 21 .(-1)
2x = - 21
x = -21/2


e) 17x - 7x = x + 18
17x - 7x - x = 18
17x - 8x = 18
9x = 18
x = 18/9
x = 2

S[2]



f)9x + 9 + 3x = 15
9x + 3x = 15 - 9
12x = 6
x = 6/12      simplifica 6 e 12 por 6
x = 1/2

S[1/2]



g) x + 2x + 3 - 5x = 4x - 9
x + 2x - 5x - 4x = - 9 - 3
3x - 9x = - 12
- 6x = - 12 .(-1)
6x = 12
x = 12/6
x = 2

S[2]