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a) 18 = 2 . 3 2 ; 30 = 2 . 3 . 5 . Từ đó ƯCLN (18; 30) = 2.3 = 6.
b) 24 = 2 3 . 3 ; 48 = 2 4 . 3 . Từ đó Ư C L N ( 24 ; 48 ) = 2 3 . 3 = 24 .
c) 18 = 2 . 3 2 ; 30 = 2 . 3 . 5 ; 15 = 3 . 5 . Từ đó ƯCLN (18; 30; 15) = 3.
d) 24 = 2 3 . 3 ; 48 = 2 4 . 3 ; 36 = 2 2 . 3 2 .
Từ đó Ư C L N ( 24 ; 48 ; 36 ) = 2 2 . 3 = 12 .
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Bài 2:
a) 11. x = -55
x = -55 : 11
x = -5
Vậy x = -5
b) -3 . x = -12
x = -12 : (-3)
x = 4
Vậy x = 4
c) 3x - 12 = -48
3x = -48 + 12
3x = -36
x = -36 : 3
x = -12
Vậy x = -12
d) 10 + 23 . (2x - 10) = -36
23 . (2x - 10) = -36 - 10
23 . (2x - 10) = -46
2x - 10 = -46 : 23
2x - 10 = -2
2x = -2 + 10
2x = 8
x = 8: 2
x = 4
Vậy x = 4
f) | 2x - 1| + 3 = 8
|2x - 1| = 8 - 3
|2x - 1| = 5
\(\Rightarrow\left[\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\Rightarrow\left[\begin{matrix}2x=6\\2x=-4\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
Vậy x = 3 hoặc x = -2
g) |2x2 - 3| - 4 = 11
|2x2- 3| = 11 + 4
|2x2 - 3| = 15
\(\Rightarrow\left[\begin{matrix}2x^2-3=15\\2x^2-3=-15\end{matrix}\right.\Rightarrow\left[\begin{matrix}2x^2=18\\2x^2=-12\end{matrix}\right.\Rightarrow\left[\begin{matrix}x^2=9\\x^2=-6\end{matrix}\right.\Rightarrow\left[\begin{matrix}x^2=3^2\\\left(loại\right)\end{matrix}\right.\Rightarrow\left[\begin{matrix}x=3\\\end{matrix}\right.\)
Vậy x = 3.
Bài 1:
\((-48) . 72 +36 . (-304) \)
\(=\left[\left(-48\right).\left(36.2\right)\right]+36.\left(-340\right)\)
\(=\left[\left(-48\right).2\right].36+36.\left(-340\right)\)
\(=\left(-96\right).36+36.\left(-304\right)\)
\(=36.\left[\left(-96\right)+\left(-304\right)\right]\)
\(=36.\left(-400\right)\)
\(=-14400\)
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a, 36:(x–5) = 2 2
(x–5) = 9
x = 14
b, [3.(70–x)+5]:2 = 46
[3.(70–x)+5] = 92
70–x = 29
x = 41
c, 450:[41–(2x–5)] = 3 2 .5
41–(2x–5) = 10
2x–5 = 31
2x = 36
x = 18
d, 230+[ 2 4 +(x–5)] = 315. 2018 0
16+(x–5) = 315–230
x–5 = 85–16
x = 69+5
x = 74
e, 2 x + 2 x + 1 = 48
2 x .(2+1) = 48
2 x = 16 = 2 4
x = 4
f, 3 x + 2 + 3 x = 2430
3 x . 3 2 + 1 = 2430
3 x = 2430:10 = 243 = 3 5
x = 5
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a, x - 1 2 = 36
ó x - 1 2 = 6 2
ó x – 1 = 6
ó x = 7
Vậy x = 7
b, 7 x - 11 3 = 2 5 . 5 2 + 200
=> 7 x - 11 3 = 800 + 200
=> 7 x - 11 3 = 1000
=> 7 x - 11 3 = 10 3
=> 7x – 11 = 10
=> 7x = 21
=> x = 3
Vậy x = 3
c, x 11 = x
=> x 11 - x = 0
=> x ( x 10 - 1 ) = 0
=>
d, x 2 = 2 3 + 3 2 + 4 3
=> x 2 = 81
=> x = 9
e, 2 x 3 3 2 = 48
=> 2 x 3 9 = 48
=> 2 x 3 = 48 . 9
=> x 3 = 216
=> x 3 = 6 3
=> x = 6
f, 2 x + 1 3 = 125
=> 2 x + 1 3 = 5 3
=> 2x + 1 = 5
=> 2x = 4
=> x = 2
Bg
48 + x - 30 = 36 - 2x
48 - 30 + x = 36 - 2x
18 + x = 36 - 2x
x = 36 - 2x - 18
x = 36 - 18 - 2x
x = 18 - 2x
x - x = 18 - 2x - x
0 = 18 - 3x
18 = 3x
18 : 3 = x
6 = x
Bài làm
\(48+x-30=36-2x\)
\(\Leftrightarrow-18+3x=0\Leftrightarrow x=\frac{18}{3}=6\)