9-10+11-12+13-14+15-16=?
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\(2^x+2^{x+1}+2^{x+2}=56\)
\(2^x\left(1+2+2^2\right)=56\)
\(2^x\cdot7=56\)
\(2^x=8\)
\(x=3\)
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a) x + 118 = 218
x = 218 – 118
x = 100
b) 18 – x = -17
X = 18 – (-17)
X = 35
c) (-18) – x = -17
X = (-18) – (-17)
X = -1
d)124 + (118 – x) = 217
118 – x = 93
X = 118 – 93
X = 25
e) (3x – 6).3 = 34
(3x – 6).3 = 81
3x – 6 = 27
3x = 33
ð X = 11
g) 23.(42 – x) = 46
42 – x = 2
ð X = 40
h) 84 – (3x + 8) = 34
3x + 8 = 84 – 34
3x + 8 = 50
3x = 50 – 8
3x = 42
X = 42 : 3
ð X = 14
i) 3.(2x + 1) – 19 = 14
3.(2x + 1) = 14 + 19
3.(2x + 1) = 33
2x + 1 = 33 : 3
2x + 1 = 11
2x = 11 – 1
2x = 10
X = 10 : 2
ð X = 5
k) 6x – 302 = 23.5
6x – 302 = 40
6x = 40 + 302
6x = 342
X = 342 : 6
ð X = 57
m) (x – 1)2 = 81
(x – 1)2 = 92
ð X – 1 = 9
ð X = 9 + 1
ð X = 10
n) 2x+1 – 5 = 27
2x+1 = 27 + 5
2x+1 = 32
2x+1 = 25
ð X = 4
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a. 24 x (-125 + 225)
= 24 x 100
=2400
b. -125 x ( 24 -36 )
= -125 x -12
= 1500
c. 512 x (2 -128+128)
= 512 x 2
= 1024
d. \([4.25].\left[\left(-2\right).\left(-5\right)\right].\left[125.\left(-8\right)\right]\)
= 100.10.(-1000)
= -1000000
a. 24 x (-125 + 225)
= 24 x 100
=2400
b. -125 x ( 24 -36 )
= -125 x -12
= 1500
c. 512 x (2 -128+128)
= 512 x 2
= 1024
d.
= 100.10.(-1000)
= -1000000
![](https://rs.olm.vn/images/avt/0.png?1311)
Vì a lớn nhất mà 480 ⋮ a; 720 ⋮ a ⇒ a = ƯCLN ( 480; 720 )
Ta có 480 = 25 . 3 . 5 720 = 24 . 32 . 5
⇒ a = ƯCLN ( 480; 720 ) = 24 . 3 . 5 = 240
Vậy a = 240
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|x - 5| + 19 = 20
|x -5 | = 20 - 19
| x - 5| = 1
\(\left[{}\begin{matrix}x-5=1\\x-5=-1\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=6\\x=4\end{matrix}\right.\)
\(x\in\) { 4; 6}
\(|x-5|=1\)
\(\left\{{}\begin{matrix}x-5=1\\x-5=-1\end{matrix}\right.\)
\(\left\{{}\begin{matrix}x=6\\x=4\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
|-19| + (-20) + (-19) + 12
= 19 - 20 - 19 + 12
= ( 19 - 19) - ( 20 - 12)
=0 - 8
= - 8
(9-10)+(11-12)+(13-14)+(15-16)
= (-1) + (-1)+( -1)+ (-1)
= -4