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a) 72,5 - (2x + 1) = 630 : 9
⇒ 72,5 - (2x + 1) = 70
⇒ 2x + 1 = 2,5
⇒ 2x = 1,5
⇒ x = 0,75
b) (10 - 4x) + 120 : 23 = 17
⇒ (10 - 4x) + 120 : 8 = 17
⇒ (10 - 4x) + 15 = 17
⇒ 10 - 4x = 2
⇒ 4x = 8
⇒ x = 2
Vậy x = 2
a) 7^2.5-(2x+1)=630:9
b) (10-4x)+120:2^3=17
c) [124-(20-4X)]:30+7=11
d) |2x-5|=1
nhớ ghi đầy đủ bước nhá
\(a\)\(.\)\(7^2.5-\left(2x+1\right)=630:9\)
\(49.5-\left(2x+1\right)=70\)
\(245-\left(2x+1\right)=70\)
\(2x+1=245-70\)
\(2x+1=175\)
\(2x=175-1\)
\(2x=174\)
\(x=174:2\)
\(x=87\)
Vậy \(x=87\)
\(b.\)\(\left(10-4x\right)+120:2^3=17\)
\(\left(10-4x\right)+120:8=17\)
\(\left(10-4x\right)+15=17\)
\(10-4x=17-15\)
\(10-4x=2\)
\(4x=10-2\)
\(4x=8\)
\(x=8:4\)
\(x=2\)
Vậy \(x=2\)
\(c.\)\(\left[124-\left(20-4x\right)\right]:30+7=11\)
\(\left[124-\left(20-4x\right)\right]:30=11-7\)
\(\left[124-\left(20-4x\right)\right]:30=4\)
\(\left[124-\left(20-4x\right)\right]=4.30\)
\(\left[124-\left(20-4x\right)\right]=120\)
\(124-20+4x=120\)
\(104+4x=120\)
\(4x=120-104\)
\(4x=16\)
\(x=16:4\)
\(x=4\)
Vậy \(x=4\)
\(d.\)\(\left|2x+5\right|=1\)
\(\Rightarrow2x+5\in\left\{-1;1\right\}\)
\(\Rightarrow2x\in\left\{-6;-4\right\}\)
\(\Rightarrow x\in\left\{-3;-2\right\}\)
Vậy \(x\in\left\{-3;-2\right\}\)
học tốt
a) \(7^2\cdot5-\left(2x+1\right)=630:9\)
\(\Leftrightarrow49\cdot5-2x-1=70\)
\(\Leftrightarrow244-2x=70\)
\(\Leftrightarrow2x=244-70\)
\(\Leftrightarrow2x=174\)
\(\Leftrightarrow x=87\)
Vậy x=87.
b) \(\left(10-4x\right)+120:2^3=17\)
\(\Leftrightarrow10-4x+120:8=17\)
\(\Leftrightarrow10-4x+15=17\)
\(\Leftrightarrow25-4x=17\)
\(\Leftrightarrow4x=25-17=8\)
\(\Leftrightarrow x=2\)
Vậy x=2
c)\([124-\left(20-4x\right)]:30+7=11\)
\(\Leftrightarrow\left(124-20+4x\right):30=4\)
\(\Leftrightarrow104+4x=120\)
\(\Leftrightarrow4x=120-104=16\)
\(\Leftrightarrow x=4\)
Vậy x=4
d) \(|2x-5|=1\)
\(\Leftrightarrow\orbr{\begin{cases}2x-5=1\\2x-5=-1\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}2x=6\\2x=4\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=2\end{cases}}\)
Vậy \(x\in\text{ }\left\{3;2\right\}\)
a) \(6x-36=5^{12}:5^{10}-2012^0\)
\(6x-36=5^2-2012^0\)
\(6x-36=25-1\)
\(6x-36=24\)
\(6x\) \(=24+36\)
\(6x\) \(=60\)
\(x=60:6\)
\(x=10\)
Vậy \(x=10\)
b) \(2x-125=-65\)
\(2x\) \(=\left(-65\right)+125\)
\(2x\) \(=60\)
\(x=60:2\)
\(x=30\)
Vậy \(x=30\)
c) \(2012-120\left(4x+1\right)=932\)
\(120\left(4x+1\right)=2012-932\)
\(120\left(4x+1\right)=1080\)
\(4x+1=1080:120\)
\(4x+1=9\)
\(4x\) \(=9-1\)
\(4x\) \(=8\)
\(x=8:4\)
\(x=2\)
Vậy \(x=2\)
a) 6x - 36 = 512 : 510 - 20120
6x - 36 = 52 - 20120
6x - 36 = 25 - 1
6x - 36 = 24
6x = 24 + 36
6x = 60
x = 60 : 6
x = 10
Vậy x = 10
b) 2x - 125 = -65
2x = (-65) + 125
2x = 60
x = 60 : 2
x = 30
Vậy x = 30
c) 2012 - 120(4x + 1) = 932
120(4x + 1) = 2012 - 932
120(4x + 1) = 1080
4x + 1 = 1080 : 120
4x + 1 = 9
4x = 9 - 1
4x = 8
x = 8 : 4
x = 2
Vậy x = 2.
Chúc bạn học tốt!
TBR, Ta có:
(100 – 4x) + 120 : 23 = 1 + 42
\(\Rightarrow\) 10 – 4x + 15 = 17
= 25 – 4x = 17 \(\Rightarrow\) 4x = 25 – 17 \(\Rightarrow\) 4x = 25 – 17
\(\Rightarrow\) 4x = 8 \(\Rightarrow\)x = 8 : 4 = 2
\(\left(10-4x\right)+120:2^3=1+4^2\)
\(\Rightarrow\) \(\left(10-4x\right)+120:8=17\)
\(\Rightarrow\) \(\left(10-4x\right)+15=17\)
\(\Rightarrow\) \(10-4x=2\)
\(\Rightarrow\) \(4x=8\)
\(\Rightarrow\) \(x=2\)
a)(x-35)-120=0 b)124+(118-x)=217 c)156-(x+61)=82
x-35 = 0+120=120 118-x =217-124=93 x+61 = 156-82=74
x = 120+35=155 x = 118-93=25 x =74-61=13
suy ra x=155 suy ra x= 25 suy ra x=13
a) ( x - 35 ) - 120 = 0
<=> x - 35 = 120
<=> x = 155
b) 124 + ( 118 - x ) = 217
<=> 118 - x = 93
<=> x = 25
c) 156 - ( x + 61 ) = 82
<=> x + 61 = 74
<=> x = 13
(x-35)-120=0
x-35 = 0 + 120
x-35 = 120
x = 120 + 35
x = 155
124+(118-x)=217
118-x = 217-124
118-x = 93
x = 118 - 93
x = 25
156-(x+61)=82
x + 61=156-82
x+61 = 74
x = 74 - 61
x = 13
(x-35)-120=0
x-35 = 0+120
x-35 = 120
x = 120-35
x = 85
124 + (118-x)=217
118-x=217-124
118-x=93
x=118-93
x=25
156-(x+61)=82
x+161=156-82
x+161=74
x=161-74
x=87
do la bai cua minh,co cho sai nao thi sua cho minh nhe
a. 2x + 70 = 74
<=> 2x = 4
<=> x = 2
b. 120 - \(\dfrac{4x}{2}\) = 80
<=> 120 - 2x = 80
<=> 120 - 80 = 2x
<=> 2x = 40
<=> x = 20
c. (3x + 5)2 = 400
<=> \(|3x+5|=\sqrt{400}\)
<=> \(|3x+5|=20\)
<=> \(\left[{}\begin{matrix}3x+5=20\\3x+5=-20\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{-25}{3}\end{matrix}\right.\)
a) ( x - 35 ) - 120 = 0
<=> x - 35 = 120
<=> x = 155
b) 124 + ( 118 - x ) = 217
<=> 118 - x = 93
<=> x = 25
a, (x - 35) - 120 = 0
=> x - 35 = 120
=> x = 155
b, 124 + (118 - x) = 217
=> 118 - x = 93
=> x = 25
c, 156 - (x + 61) = 82
=> x + 61 = 74
=> x = 13
\(120:\left(124-4x\right)-10=5\)
\(120:\left(124-4x\right)=5+10\)
\(120:\left(124-4x\right)=15\)
\(124-4x=120:15\)
\(124-4x=8\)
\(4x=124-8\)
\(4x=116\)
\(x=116:4=29\)
=>120:[124-4x]=15
=>[124-4x]=8
=>-4x=8-124
=>-4x=-116
=>x=29
Vậy x=29