tìm x \(\in\)Z
a, ( x - 5 )\(^6\)= ( x- 5 )\(^8\)
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Câu 1:
a) Ta có: x-3 là ước của 13
\(\Leftrightarrow x-3\inƯ\left(13\right)\)
\(\Leftrightarrow x-3\in\left\{1;-1;13;-13\right\}\)
hay \(x\in\left\{4;2;16;-10\right\}\)(thỏa mãn)
Vậy: \(x\in\left\{4;2;16;-10\right\}\)
b) Ta có: \(x^2-7\) là ước của \(x^2+2\)
\(\Leftrightarrow x^2+2⋮x^2-7\)
\(\Leftrightarrow x^2-7+9⋮x^2-7\)
mà \(x^2-7⋮x^2-7\)
nên \(9⋮x^2-7\)
\(\Leftrightarrow x^2-7\inƯ\left(9\right)\)
\(\Leftrightarrow x^2-7\in\left\{1;-1;3;-3;9;-9\right\}\)
mà \(x^2-7\ge-7\forall x\)
nên \(x^2-7\in\left\{1;-1;3;-3;9\right\}\)
\(\Leftrightarrow x^2\in\left\{8;6;10;4;16\right\}\)
\(\Leftrightarrow x\in\left\{2\sqrt{2};-2\sqrt{2};-\sqrt{6};\sqrt{6};\sqrt{10};-\sqrt{10};2;-2;4;-4\right\}\)
mà \(x\in Z\)
nên \(x\in\left\{2;-2;4;-4\right\}\)
Vậy: \(x\in\left\{2;-2;4;-4\right\}\)
Câu 2:
a) Ta có: \(2\left(x-3\right)-3\left(x-5\right)=4\left(3-x\right)-18\)
\(\Leftrightarrow2x-6-3x+15=12-4x-18\)
\(\Leftrightarrow-x+9+4x+6=0\)
\(\Leftrightarrow3x+15=0\)
\(\Leftrightarrow3x=-15\)
hay x=-5
Vậy: x=-5
a) Ta có: -7<x<-1
mà \(x\in Z\)
nên \(x\in\left\{-6;-5;-4;-3;-2\right\}\)
Vậy: \(x\in\left\{-6;-5;-4;-3;-2\right\}\)
b) Ta có: -3<x<3
mà \(x\in Z\)
nên \(x\in\left\{2;1;0;1;2\right\}\)
Vậy: \(x\in\left\{2;1;0;1;2\right\}\)
c) Ta có: \(-1\le x\le6\)
mà \(x\in Z\)
nên \(x\in\left\{-1;0;1;2;3;4;5;6\right\}\)
Vậy: \(x\in\left\{-1;0;1;2;3;4;5;6\right\}\)
d) Ta có: \(-5\le x< 6\)
mà \(x\in Z\)
nên \(x\in\left\{-5;-4;-3;-2;-1;0;1;2;3;4;5\right\}\)
Vậy: \(x\in\left\{-5;-4;-3;-2;-1;0;1;2;3;4;5\right\}\)
a: Bạn ghi lại đề nha bạn
b: \(30\left(x+2\right)-6\left(x-5\right)-24x=100\)
=>\(30x+60-6x+30-24x=100\)
=>\(\left(30x-6x-24x\right)+\left(60+30\right)=100\)
=>0x=100-90=10(vô lý)
c: \(\left(x-7\right)\left(x+3\right)< 0\)
TH1: \(\left\{{}\begin{matrix}x-7>0\\x+3< 0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x>7\\x< -3\end{matrix}\right.\)
=>\(x\in\varnothing\)
TH2: \(\left\{{}\begin{matrix}x-7< 0\\x+3>0\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x< 7\\x>-3\end{matrix}\right.\)
=>-3<x<7
mà x nguyên
nên \(x\in\left\{-2;-1;0;1;2;3;4;5;6\right\}\)
d: -1<2x-1<4
=>\(-1+1< 2x< 4+1\)
=>0<2x<5
=>0<x<2,5
mà x nguyên
nên \(x\in\left\{1;2\right\}\)
a: x(x+5)=0
=>\(\left[{}\begin{matrix}x=0\\x+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)
b: 2x(x+3)=0
=>x(x+3)=0
=>\(\left[{}\begin{matrix}x=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-3\end{matrix}\right.\)
c: \(\left(6-x\right)\left(x+10\right)=0\)
=>\(\left[{}\begin{matrix}6-x=0\\x+10=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6-0=6\\x=0-10=-10\end{matrix}\right.\)
d: \(\left(5x+20\right)\left(x^2+1\right)=0\)
=>\(5x+20=0\left(x^2+1>=1>0\forall x\right)\)
=>5x=-20
=>x=-4
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}
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: \(15\cdot\left(-19-4\right)-19\cdot\left(15-4\right)\)
\(=-15\cdot19-15\cdot4-15\cdot19+19\cdot4\)
\(=-30\cdot19+4\cdot4\)
\(=-2\cdot\left(15\cdot19+2\cdot4\right)\)
\(=-2\cdot\left(285+8\right)=-586\)
a: =>5-x=-23
=>x=5+23=28
b: =>x-3-x+7-25+x=54
=>x-21=54
=>x=75
c: =>7-9x-2x+4=-5x-35+27-25=-5x-37
=>-11x+3=-5x-37
=>-6x=-40
=>x=20/3
a.
10-x-5 = (-5) - 7 -11
=>5-x = 0
=>x=5
b
(x-3) - (x+17-24) - (25-x) = 24 - (-30)
=>x - 3 - x - 17 + 24 - 25 - x = 24 + 30
=>-x - 21 = 54
=>-x = 75
=>x = -75
c
(7 - 9x) - (2x - 4) = - (5x + 35) - (-27) - 25
=>7-9x - 2x + 4 = -5x - 35 + 27 - 35
=>11 - 11x + 5x = -43
=>16x = 11 + 43
=>16x = 54
=>x=4
1: x=3/4-1/2=3/4-2/4=1/4
2: x-1/5=2/11
=>x=2/11+1/5=21/55
3: x-5/6=16/42-8/56
=>x-5/6=8/21-4/28=5/21
=>x=5/21+5/6=15/14
4: x/5=5/6-19/30
=>x/5=25/30-19/30=6/30=1/5
=>x=1
5: =>|x|=1/3+1/4=7/12
=>x=7/12 hoặc x=-7/12
6: x=-1/2+3/4
=>x=3/4-1/2=1/4
11: x-(-6/12)=9/48
=>x+1/2=3/16
=>x=3/16-1/2=-5/16
1)x= 1/4
2)x= 2/11+ 1/5
x= 21/55
3)x - 5/6 = 5/21
x = 5/21+5/6
x = 15/14
4)x/5 = 5/6 + -19/30
x:5 = 1/5
x = 1/5.5
x = 1
5) |x| - 1/4 = 6/18
|x| = 6/18 - 1/4
|x| =7/12
⇒x= 7/12 hoặc -7/12
6)x = -1/2 +3/4
x= 1/4
7) x/15 = 3/5 + -2/3
x:15 = -1/15
x = -1/15. 15
x = -1
8)11/8 + 13/6 = 85/x
85/24 = 85/x
⇒ x = 24
9) x - 7/8 = 13/12
x = 13/12 + 7/8
x = 47/24
10)x - -6/15 = 4/27
x = 4/27 + (-6/15)
x = -34/135
11) -(-6/12)+x = 9/48
x= 9/48 - 6/12
x = -5/16
12) x - 4/6 = 5/25 + -7/15
x -4/6 = -4/15
x = -4/15 + 4/6
x = 2/5
\(\left(x-5\right)^6=\left(x-5\right)^8\)
\(\Leftrightarrow\left(x-5\right)^8-\left(x-5\right)^6=0\)
\(\Leftrightarrow\left(x-5\right)^6\left[\left(x-5\right)^2-1\right]=0\)
\(\Rightarrow\orbr{\begin{cases}\left(x-5\right)^6=0\\\left(x-5\right)^6-1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=5\\\orbr{\begin{cases}x=6\\x=4\end{cases}}\end{cases}}\)