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\(a)\left(x-5\right).2=0\)
\(\Rightarrow x-5=0\)
\(\Rightarrow x=5\)
Vậy \(x=5\)
\(b)x.3-13=47\)
\(\Rightarrow x.3=47+13\)
\(\Rightarrow x.3=60\)
\(\Rightarrow x=60:3\)
\(\Rightarrow x=20\)
Vậy \(x=20\)
\(c)\left(x.7-7\right)\left(x.12+24\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x.7-7=0\Rightarrow x.7=7\Rightarrow x=1\\x.12+24=0\Rightarrow x.12=-24\Rightarrow x=-2\end{cases}}\)
Vậy\(x\in\left\{1;-2\right\}\)
\(e)140-10.x=120\)
\(\Rightarrow10.x=140-120\)
\(\Rightarrow10.x=20\)
\(\Rightarrow x=2\)
Vậy \(x=2\)
\(g)x.5-127=273\)
\(\Rightarrow x.5=273+127\)
\(\Rightarrow x.5=400\)
\(\Rightarrow x=400:5\)
\(\Rightarrow x=80\)
Vậy \(x=80\)
a, x= 155 -51 <=> x=104
b.x=-120 : -24 <=> x=5
c.2(81-x)= 155 -35
<=> 2(81-x)=120
<=> 81 - x = 60
<=> x= 21
Lời giải:
a.
$155-x=51$
$x=155-51=104$
b.
$(-24)x=-120$
$x=(-120):(-24)=5$
c.
$35+2(81-x)=155$
$2(81-x)=155-35=120$
$81-x=120:2=60$
$x=81-60=21$
a) 5x - 14 = x - 34
5x - x = -34 + 14
4x = -20
x = -20 : 4
x = -5
b) x - 3 - (3x + 2) = -15
x - 3 - 3x - 2 = -15
x - 3x = -15 + 3 + 2
-2x = -10
x = (-10) : (-2)
x = 5
c) 2(x - 12) + 19 = x + (-34)
2x - 24 + 19 = x + (-34)
2x - x = -34 + 24 - 19
x = -29
d) 2(x - 33) - 3(x - 43) = 96 - 115
2x - 66 - 3x + 129 = 96 - 115
2x - 3x = 96 - 115 + 66 - 129
-x = -82
x = 82
e) 2x + 3 - 9x = -11
2x - 9x = -11 - 3
-7x = -14
x = (-14) : (-7)
x = 2
f) -(x + 3 - 84) = (x + 70 - 71) - 6
-x - 3 + 84 = x + 70 - 71 - 6
-x - x = 70 - 71 - 6 - 84
-2x = -91
x = (-91) : (-2)
x = 45,5
a,-2x -(x-17)=34-(-x+25)
-2x-x+17=34+x-25
-3x+17=9+x
-3x-x=9-17
-4x=-8
-->4x=8
x=8:4
x=2
Vậy x=2
b,17-(16x-37)=2x+43
17-16x+37=2x+43
20-16x=2x+43
-16x-2x=43-20
-18x=23
x=23:(-18)
x=23/-18
Mà x là số nguyên nên --> x thuộc tập rỗng
c,-2x-3.(x-17)=34-2(-x+25)
-2x-3x+51=34-2.(-x)-25
-5x+51=9-(-2).x
-5x+(-2).x=9-51
-7x=-42
7x=42
x=42:7
x=6
Vậy x=6
Bài làm :
\(a\text{)}...\Leftrightarrow\orbr{\begin{cases}x\div7-7=0\\x.3-12=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x\div7=7\\x.3=12\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=49\\x=4\end{cases}}\)
\(b\text{)}\Leftrightarrow...\Leftrightarrow x\div2=15\Leftrightarrow x=15.2=30\)
\(c\text{)}...\Leftrightarrow100\div x=20\Leftrightarrow x=100\div20=5\)
\(d\text{)}...\Leftrightarrow x\div5=27\Leftrightarrow x=27.5=135\)
36 x 12 + 36 x 45 + 36 x 33
= 36 x (12 + 45 + 33)
= 36 x 90
= 3240
b) 78 x 31 + 78 x 24 + 78 x 17 + 22 x 72
=78 x (31 + 24 + 17) + 22 x 72
= 78 x 72 + 22 x 72
= (78 + 22) x 72
= 100 x 72
= 7200
c) ( 34 - 17 )2 - 23 x 32
\(=17^2-8.9\)
\(=289-72\)
\(=217\)
`@` `\text {Ans}`
`\downarrow`
`a)`
`2 \times x + 34 = 168`
`=> 2x = 168 - 34`
`=> 2x = 134`
`=> x = 134 \div 2`
`=> x = 67`
Vậy, `x=67`
`b)`
`x \times 11 + 51 = 273`
`=> 11x = 273 - 51`
`=> 11x = 222`
`=> x = 222 \div 11`
`=> x = 222/11`
`c)`
`x \div 120 - 45 = 155`
`=> x \div 120 = 155 + 45`
`=> x \div 120 = 200`
`=> x = 200 \times 120`
`=> x = 24000`
Vậy, `x = 24000`
`d)`
`320 \div x - 127 = 33`
`=> 320 \div x = 33+127`
`=> 320 \div x = 160`
`=> x = 320 \div 160`
`=> x = 2`
Vậy, `x=2.`
`@` `\text {Kaizuu lv uuu}`
a)2 x x +34 =168
2 x X = 168 - 34
2 x X = 134
X= 134:2
X= 67
b) x x 11 + 51 = 273
X x 11 = 273 - 51
X x 11= 222
X= 222 :11
X= 222/11
c) x : 120 – 45 = 155
x:120= 155+45
x:120=200
x=200:120
x=5/3
d) 320 : x – 127 = 33
320: x= 33+127
320:x=160
x=320:160
x=2