Excontre o valor de
x nas seguintes equaçóes abaixo.
a) 2x + 4 = 9
b) x – 5 = - 6x
c) 4x + 40 -3x = 2x – 5x
d) x + x+3 = 9x +x – 12
e) 90 – 30x = 0
f) 5x + 4 = 20x
g) 10x – 2 = 3x + 7x
h) 3x+3 = 6x – 21
i) 40 – 80x + 20x = 5
j) 100 = 6x-2x
Respostas
Explicação:
a) 2x + 4 = 9
2x = 9 - 4
2x = 5
x = 5
2
____________
b) x - 5 = -6x
x - 6x = + 5
7x = 5
x = 5
7
______________
c) 4x + 40 -3x = 2x – 5x
4x - 3x + 40 = -3x
1x + 3x = -40
x = - 40
4
x = -10
_______________
d) x + x + 3 = 9x + x – 12
x + 3 = 9x - 12
x - 9x = -12 + 3
-8x = -15
x = 15
8
________________
e) 90 – 30x = 0
-30x = 0 - 90
x = -90
-30
x = 3
_________________
f) 5x + 4 = 20x
5x - 20x = -4
-15x = -4
x = 4
15
___________________
g) 10x – 2 = 3x + 7x
10x - 2 = 10x
10x - 10x = 2
x = 0
___________________
h) 3x+3 = 6x – 21
3x - 6 x = - 21 - 3
-3x = -24
x = -24
-3
x = 8
___________________
i) 40 – 80x + 20x = 5
-60x = 5 - 40
-60x = -35
x = -35 --> x = 7
-60. 12
___________________
j) 100 = 6x-2x
100 = 4x
-4x = -100
x = -100
-4
x = 25
___________________