Question

Câu 1. Thực hiện các phép tính sau:

a) 12 : { 400 : [500 – (125 + 25 . 7)]}                                b) 5 . 2² – 18 : 3

c) 18 : 3 + 182 + 3.(51 : 17)                                  d) 25 . 8 – 12.5 + 170:17 - 8

Câu 2: Tìm x biết:

a) 12 + (5 + x) = 20                                                        b) 175 + (30 – x) = 200

c) 10 + 2x = 4⁵ : 4³                                                         d) 10x + 2².5 = 10²

Answer 1

Câu 2: 

a: \(\Leftrightarrow x+5=8\)

hay x=3

b: \(\Leftrightarrow30-x=25\)

hay x=5

Answer 2

Câu 1 : 

a) 12 : { 400 : [ 500 - ( 125 + 25 . 7 )]}

= 12 : { 400 : [ 500 - ( 125 + 175 )]}

= 12 : { 400 : [ 500 - 300 ]}

= 12 : { 400 : 200 }

= 12 : 2

= 6

b) 5 . 2² - 18 : 3

= 5 . 4 - 18 : 3

= 20 - 6

= 14

c) 18 : 3 + 182 + 3.(51 : 17)

= 6 + 182 + 3.3

= 6 + 182 + 9

= 197

d) 25 .8 - 12.5 + 170 : 17 - 8 

= 200 - 60 + 10 - 8

= 140 + 10 - 8 

= 150 - 8

= 142

 

Answer 3

Câu 2 : 

a) 12 + (5+x) = 20

5 + x = 20 - 12

5 + x = 8

x = 8 - 5 

x = 3

b) 175 + (30 - x ) = 200

30 - x = 200 - 175 

30 - x = 25

x = 30 - 25

x = 5

c) 10 + 2x = 4⁵ : 4³

10 + 2x = 4²

10 + 2x = 16

2x = 16 - 10

2x = 6

x = 6 : 2

x = 3

d) 10x + 2² . 5 = 10²

10x + 4 . 5 = 100

10x = 100 : 20

10x = 5 

x = 0,5