Question

determine o valor de x nas sentenças:
a) 3(x+4)=42

b) 2x-2+3=13

c) 4x+17=21

d) x=(120÷4) x 5

Answer 1

a) 3(x+4)=12
    3x+12=12
    3x=+12-12
    x=3

b) 2x-2+3=13
    2x=+2-3+13
    2x= 12
    x=$\frac{12}{2}$
    x=6

c) 4x+17=21
    4x=-17+21
    4x=4
    x= $\frac{4}{4}$
    x=1

d)x=(120÷4)x 5
   x=30 x 5 
   x= 150 

Answer 2

a) 3(x + 4) = 42
3x + 12 = 42
3x = 42 - 12
3x = 30
x = 30/3
x = 10

b) 2x - 2 + 3 = 13
2x = 13 + 2 - 3
2x = 12
x = 12/2
x = 6

c) 4x + 17 = 21
4x = 21 - 17 
4x = 4
x = 4/4
x = 1

d) x = (120 : 4) .5
x = 30 . 5
x= 150