## Bài 1:Tìm * a)123-5x(*+4)=38 b)70-5x(*-3)=45 c)71+(26-3x*):5=75

Question

Bài 1:Tìm *
a)123-5x(*+4)=38
b)70-5x(*-3)=45
c)71+(26-3x*):5=75

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6 phút 2021-09-07T10:31:40+00:00 2 Answers 0 views 0

1. $\text { a) 123 – 5 x (* + 4) = 38 }$

$\text { 5 x (* + 4) = 123 – 38 }$

$\text { 5 x (* + 4) = 85 }$

$\text { * + 4 = 85 : 5 }$

$\text { * + 4 = 17 }$

$\text { * = 17 – 4 }$

$\text { * = 13 }$

$\text { b) 70 – 5 x (* – 3) = 45 }$

$\text { 5 x (* – 3) = 70 – 45 }$

$\text { 5 x (* – 3) = 25 }$

$\text { * – 3 = 25 : 5 }$

$\text { * – 3 = 5 }$

$\text { * = 5 + 3 }$

$\text { * = 8 }$

$\text { c) 71 + (26 – 3 x *) : 5 = 75 }$

$\text { (26 – 3 x *) : 5 = 75 – 71 }$

$\text { (26 – 3 x *) : 5 = 4 }$

$\text { 26 – 3 x * = 4 x 5 }$

$\text { 26 – 3 x * = 20 }$

$\text { 3 x * = 26 – 20 }$

$\text { 3 x * = 6 }$

$\text { * = 6 : 3 }$

$\text { * = 2 }$

2. a)123-5xx(x+4)=38

5xx(x+4)=123-38

5xx(x+4)=85

x+4=85:5

x+4=17

x=17-4

x=13

b)70-5xx(x-3)=45

5xx(x-3)=70-45

5xx(x-3)=25

x-3=25:5

x-3=5

x=5+3

x=8

c)71+(26-3xxx):5=75

(26-3xxx):5=75-71

(26-3xxx):5=4

26-3xxx=4xx5

26-3xxx=20

3xxx=26-20

3xxx=6

x=6:3

x=2