Question

Tìm x biết
a) 350 - ( 3 . x ) : 75 = 170 - 69
b) 3/4 + 1/4 : x = -3
c) 5,5x + 1 = 13/15
d) 3/7 - x = 1/4 - ( -3/5 )

Answer 1

Tìm x biết
a) 350 - ( 3 . x ) : 75 = 170 - 69
350 - ( 3 . x ) : 75 = 101
( 3 . x ) : 75 = 350 - 101
( 3 . x ) : 75 = 249
3 . x = 249 . 75
3 . x = 18675
x = 18675 : 3
x = 6225
b) 3/4 + 1/4 : x = -3
1/4 : x = -3 - 3/4
1/4 : x = -15/4
x = 1/4 : -15/4
x = -1/15
c) 5,5x + 1 = 13/15
11/2x = 13/15 - 1
11/2x = -2/15
x = -2/15 : 11/2
x = -4/165
d) 3/7 - x = 1/4 - ( -3/5 )
3/7 - x = 1/4 +3/5
3/7 - x = 17/20
x = 3/7 - 17/20
x = -59/140

Answer 2

Tìm x biết :
a) 350 - ( 3 . x ) : 75 = 170 - 69

*Giải :

a) 350 - (3.x) : 75 = 170 -69

350 - ( 3.x) : 75 = 101

(3.x) : 75 = 350 - 101

( 3.x): 75 = 249

(3.x) = 249 .75

( 3. x ) = 18675

x = 18675 : 3

=> x = 6225

Vậy x = 6225 .

b) 3/4 + 1/4 : x = -3

*Giải :b) 3/4 + 1/4 : x = -3

1/4 : x = -3 -3/4

1/4 : x = -15/4

x =1/4 : ( -15/4 )

=> x = -1/15

Vậy x = -1/15 .

c)5,5x +1 = 13/15

*Giải : c) 5,5 x +1 = 13/15

11/2x = 13/15 -1

11/2x = -2/15

x = -2/15:11/2

=> x = -4/165

Vậy x = -4/165

d) 3/7 - x = 1/4 - ( -3/50)

*Giải : d) 3/7 - x = 1/4 - (-3/50)

3/7 - x = 1/4 + 3/5

3/7 - x = 17/20

x = 3/7 - 17/20

=> x = -59/140

Vậy x = -59/140

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