Tìm x biết:
a) 11 - (|x| - 7) = -21
b) -5 + (|x| + 13) = |-4|
c) |x| - 300 = -190
d) -261 + |x| = 315
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1 tháng 2 2021
câu 1:
a) 500-(300)-190+(-210)
= 500-300-190-210
= 200 - 210 -190
=-10 - 190
=-200
b) (-3)3 .5+12.(-6)
= -27.5 -72
=-135 - 72
=-207
c) 15.(-19-4)-19.(15-4)
= 15.(-23) - 19.11
=-345 - 209
=-554
câu 2: tìm x thuộc Z
a) 3x-2=3
=> 3x=3/2
=> x=1/2
b) x chia hết cho 5 và -7<x<11
=> x thuộc {-5;0;5;10}
1 tháng 2 2021
Câu 1:
a) Ta có: \(500-\left(300\right)-190+\left(-210\right)\)
\(=500-300-190-210\)
\(=\left(500-300\right)-\left(190+210\right)\)
\(=200-400=-200\)
b) Ta có: \(\left(-3\right)^3\cdot5+12\cdot\left(-6\right)\)
\(=\left(-3\right)^3\cdot5-3\cdot4\cdot3\cdot2\)
\(=-5\cdot3^3-3^2\cdot8\)
\(=3^2\cdot\left(-5\cdot3-8\right)\)
\(=9\cdot\left(-15-8\right)=9\cdot\left(-23\right)=-207\)
c) Ta có: \(15\cdot\left(-19-4\right)-19\cdot\left(15-4\right)\)
\(=-15\cdot19-15\cdot4-15\cdot19+19\cdot4\)
\(=-30\cdot19+4\cdot4\)
\(=-2\cdot\left(15\cdot19+2\cdot4\right)\)
\(=-2\cdot\left(285+8\right)=-586\)
12 tháng 8 2020
11/13-(5/42-x)=(15/28-11/13)
11/13-(5/42-x)=-37/182
(5/42-x)=11/13+37/182
(5/42-x)=191/182
x=5/42-191/182
x=-254/273
vậy x=-254/273
27 tháng 1 2018
a) ( x -21 * 13) : 11 = 39 => x - 21*13 = 39 * 11 => x - 273 = 429 => x= 429 + 273 => x= 702 b) ( x - 21) * 13 : 11 = 39 => (x-21)*13=39:11 => (x-21)*13=429 => x-21=429:13 => x-21=33 => x=33+21 => x=54
H9
HT.Phong (9A5)
CTVHS
26 tháng 10 2023
a) \(x+5=20-\left(12-7\right)\)
\(\Rightarrow x+5=20-5\)
\(\Rightarrow x+5=15\)
\(\Rightarrow x=15-5\)
\(\Rightarrow x=10\)
b) \(15-\left(3+2x\right)=2^2\)
\(\Rightarrow3+2x=15-4\)
\(\Rightarrow3+2x=11\)
\(\Rightarrow2x=11-3\)
\(\Rightarrow2x=8\)
\(\Rightarrow x=\dfrac{8}{2}\)
\(\Rightarrow x=4\)
c) \(-11-\left(19-x\right)=50\)
\(\Rightarrow19-x=-11-50\)
\(\Rightarrow19-x=-61\)
\(\Rightarrow x=61+19\)
\(\Rightarrow x=80\)
d) \(159-\left(25-x\right)=43\)
\(\Rightarrow25-x=159-43\)
\(\Rightarrow25-x=116\)
\(\Rightarrow x=25-116\)
\(\Rightarrow x=-91\)
e) \(\left(79-x\right)-43=-\left(17-52\right)\)
\(\Rightarrow\left(79-x\right)-43=52-17\)
\(\Rightarrow79-x-43=35\)
\(\Rightarrow36-x=35\)
\(\Rightarrow x=1\)
f) \(\left(7+x\right)-\left(21-13\right)=32\)
\(\Rightarrow7+x-8=32\)
\(\Rightarrow x-1=32\)
\(\Rightarrow x=32+1\)
\(\Rightarrow x=33\)
g) \(-x+20=-15+8+13\)
\(\Rightarrow-x+20=6\)
\(\Rightarrow x=20-6\)
\(\Rightarrow x=14\)
h) \(-\left(-x+13-142\right)+18=55\)
\(\Rightarrow x-13+142+18=55\)
\(\Rightarrow x+147=55\)
\(\Rightarrow x=55-147\)
\(\Rightarrow x=-92\)
CM
20 tháng 4 2017
a) x - 7 = 5. 0 => x - 7 = 0 =>x = 7.
b) x: 3 = 47 +13 => x: 3 = 60 => x = 60.3 => x = 180.
c) x : 7 - 7 = 0 hoặc x : 12 - 12 = 0. Do đó x = 49 hoặc x = 144.
d) x : 2 = 150 - 135 => x: 2 = 15 => x = 15.2 => x = 30.
e) 100: x = 140 -120 => 100: x = 20 => x = 100:20 => x = 5.
g) x : 5 = 300 - 273 => x : 5 = 27 =>x = 27.5 => x = 135
CM
12 tháng 8 2019
a) x - 7 = 5. 0 => x - 7 = 0 =>x = 7.
b) x: 3 = 47 +13 => x: 3 = 60 => x = 60.3 => x = 180.
c) x : 7 - 7 = 0 hoặc x : 12 - 12 = 0. Do đó x = 49 hoặc x = 144.
d) x : 2 = 150 - 135 => x: 2 = 15 => x = 15.2 => x = 30.
e) 100: x = 140 -120 => 100: x = 20 => x = 100:20 => x = 5.
g) x : 5 = 300 - 273 => x : 5 = 27 =>x = 27.5 => x = 135
5 tháng 3 2022
a,\(\frac{1}{5}\times\frac{2}{9}\div\frac{1}{15}\)
\(=\frac{1}{5}\times\frac{2}{9}\times15\)
\(=\left(\frac{1}{5}\times15\right)\times\frac{2}{9}\)
\(=3\times\frac{2}{9}\)
\(=\frac{2}{3}\)
b\(\frac{4}{15}\times\frac{7}{15}\times\frac{5}{4}\)
\(=\left(\frac{4}{15}\times\frac{5}{4}\right)\times\frac{7}{15}\)
\(=\frac{1}{3}\times\frac{7}{15}\)
\(=\frac{7}{45}\)
c,\(\frac{21}{23}\times\frac{5}{11}\times\frac{44}{?}\)
d,\(26\times\frac{13}{42}\div13\)
\(=\left(26\div13\right)\times\frac{13}{42}\)
\(=2\times\frac{13}{42}\)
\(=\frac{13}{21}\)
a) \(11-\left(\left|x\right|-7\right)=-21\)
=> \(\left|x\right|-7=11-\left(-21\right)\)
=> \(\left|x\right|-7=32\)
=> \(\left|x\right|=32+7\)
=> \(\left|x\right|=49\)
=> \(\left[{}\begin{matrix}x=49\\x=-49\end{matrix}\right.\)
Vậy \(x=\left[{}\begin{matrix}49\\-49\end{matrix}\right.\)
b) \(-5+\left(\left|x\right|+13\right)=\left|-4\right|\)
=> \(-5+\left(\left|x\right|+13\right)=4\)
=> \(\left|x\right|+13=4-\left(-5\right)\)
=> \(\left|x\right|+13=9\)
=> \(\left|x\right|=9-13\)
=> \(\left|x\right|=-4\)
mà \(\left|x\right|\le x\)
=> \(x=\varnothing\)
Vậy \(x=\varnothing\)
c) \(\left|x\right|-300=-190\)
=> \(\left|x\right|=-190+300\)
=> \(\left|x\right|=110\)
=> \(\left[{}\begin{matrix}x=100\\x=-100\end{matrix}\right.\)
Vậy \(x=\left[{}\begin{matrix}100\\-100\end{matrix}\right.\)
d) \(-261+\left|x\right|=315\)
=> \(\left|x\right|=315-\left(-261\right)\)
=> \(\left|x\right|=576\)
=> \(\left[{}\begin{matrix}x=576\\x=-576\end{matrix}\right.\)
Vậy \(x=\left[{}\begin{matrix}576\\-576\end{matrix}\right.\)