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a) 115 + 5 ( x – 4 ) = 120
5 ( x – 4 ) = 120 – 115
5 ( x – 4 ) = 5
x – 4 = 5 : 5
x – 4 = 1
x = 1 + 4
x = 5
b) 5|x| – 10 0 = 3 7 : 3 5
5| x | – 1 = 3 2
5| x | = 9 + 1
5| x | = 10
| x | = 2
x = 2 hoặc x = -2
c) 2 2016 . 2 x - 1 = 2 2015
2 x - 1 = 2 2015 : 2 2016
2 x - 1 = 2 2015 - 2016
2 x - 1 = 2 - 1
⇒ x – 1 = -1
x = -1 + 1
x = 0
Ta có:
\(115+5\left(x-4\right)=120\)
\(5\left(x-4\right)=120-115=5\)
\(\Rightarrow x-4=1\Rightarrow x=5\)
115+5(x-4)=120
5(x-4)=120-115
5(x-4)=5
x-4=5:5
x-4=1
x =1+4
x =5
Bài 2:
a: 4x+320=480
=>4x=160
hay x=40
b: 150-x:7=120
=>x:7=30
hay x=210
a) 7(2x-1)=(346.124)-346
14x-7=42558
14x=42551
x=42551/14
b) 4/3+2(5+7x)=23
2(5+7x)=65/3
5+7x=65/6
7x=35/6
x=5/6
a) 346.124-7.(2x-1)=343
346.124-14x+7=343
42904-14x+7=343
-14x=343-42904-7
-14x=-42568
x=\(\dfrac{-42568}{-14}\)=\(\dfrac{42568}{14}\)=3,04
vậy x = 3,04
b)\(\dfrac{4}{3}\)+2(5+7x)=115:5
\(\dfrac{4}{3}\)+10+14x=23
14x=23-10-\(\dfrac{4}{3}\)
14x= \(\dfrac{35}{3}\)
x=\(\dfrac{35}{3}\):14
x=\(\dfrac{35}{42}\)=\(\dfrac{5}{6}\)
Tìm x :
346 . 124 - 7 . ( 2x - 1 ) = 346
7 . ( 2x - 1 ) = ( 346 . 124 ) - 346
7. ( 2x - 1 ) = 346 . 123
7 . 2x - 7 .1 = 42558
7 . 2x = 42558 - 7
7.2. x = 42551
14 . x = 42551
=> x = \(\dfrac{42551}{14}\)
Vậy : x = \(\dfrac{42551}{14}\)
b) \(\dfrac{4}{3}\) +2 . ( 5 + 7x ) = 115 : 5
\(\dfrac{4}{3}\) + 2. 5 + 2 . 7.x = 23
\(\dfrac{4}{3}\) + 10 + 14 . x = 23
\(\dfrac{4}{3}\) + 24 . x = 23
=> \(\dfrac{76}{3}\) . x = 23
=> x = 23 : \(\dfrac{76}{3}\)
=> x = \(\dfrac{69}{76}\)
Vậy x = \(\dfrac{69}{76}\)
a) 115 + 5 ( x – 4 ) = 120
5 ( x – 4 ) = 120 – 115
5 ( x – 4 ) = 5
x – 4 = 5 : 5
x – 4 = 1
x = 1 + 4
x = 5