Question

Bài 8: tìm x

a) x + 10 = 20

b) 2 . x + 15 = 35

c) 3 ⋅ ( x + 2 ) = 15

d) 10 . x + 15 . 11 = 20 . 10

e) 4 . ( x + 2 ) = 3 . 4

f) 33 x + 135 = 26 . 9

g) 2 . x + 15 + 16 + 17 = 100

h) 2 . (x + 9 + 10 + 11) = 4 . 12 . 25

Answer 1

a) x + 10 = 20

<=> x = 20 - 10 = 10

Vậy x = 10

b) 2x + 15 = 35

<=> 2x = 35 - 15 = 20

<=> x = 10

Vậy x = 10

c) 3(x + 2) = 15

<=> x + 2 = 15 : 3 = 5

<=> x = 5 - 2 = 3

Vậy x = 3

d) 10x + 15.11 = 20.10

<=> 10x + 165 = 200

<=> 10x = 200 - 165 = 35

<=> x = 35 : 10 = 3,5

Vậy x = 3,5

e) 4(x + 2) = 3.4

<=> x + 2 = 3

<=> x = 3 - 2 = 1

Vậy x = 1

f) 33x + 135 = 26.9

<=> 33x + 135 = 234

<=> 33x = 234 - 135 = 99

<=> x = 99 : 33 = 3

Vậy x = 3

g) 2x + 15 + 16 + 17 = 100

<=> 2x + 48 = 100

<=> 2x = 100 - 48 = 52

<=> x = 52 : 2 = 26

Vậy x = 26

h) 2(x + 9 + 10 + 11) = 4.12.5

<=> x + 30 = 120

<=> x = 120 - 30 = 90

Vậy x = 90