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a, -5/7+ 1+ 30/-7< x < -1/6+ 1/3 +5/6
<=> -4< x <1
<=> x = -3; -2; -1; 0
a, \(\dfrac{-5}{7}+1+\dfrac{30}{-7}\le x\le\dfrac{-1}{6}+\dfrac{1}{3}+\dfrac{5}{6}\)
<=> -4 \(\le x\le1\)
Do x \(\in Z\Rightarrow x=-4;-3;-2;-1;0;1\)
b, \(\dfrac{1}{2}-\left(\dfrac{1}{3}+\dfrac{1}{4}\right)< x< \dfrac{1}{48}-\left(\dfrac{1}{16}-\dfrac{1}{6}\right)\)
<=> -\(\dfrac{1}{12}< x< \dfrac{1}{8}\)
Do x \(\in Z\Rightarrow x=0;1\)
@Mai Tran
1) x - 2 = -6
x = -6 + 2
x = -4
2) -5 . x - ( -3 ) =13
-5 . x = 13 + ( -3 )
-5 . x = 10
x = 10 : ( -5 )
x = -2
a)(x+1)+(x+2)+...+(x+30)=795
(x+x+...+x)+(1+2+3+...+30)=795
30x+465=795
30x=795-465
30x=330
x=330/30
x=11
b)(x+1)+(x+3)+...+(x+99)=5100
(x+x+...+x)+(1+3+...+99)=5100
50x+2500=5100
50x=5100-2500
50x=2600
x=2600/50
x=52
1) 5.( x - 6 ) - 2.( x + 9 ) = 21
5x - 30 - 2x - 18 = 21
3x - 48 = 21
3x = 21 + 48
3x = 69
x = 23
2) 2.( x + 3 ) + 3.( x + 1 ) = 15 - ( - 9 )
2x + 6 + 3x + 3 = 24
5x + 9 = 24
5x = 24 - 9
5x = 15
x = 3
3) ( - x + 5 ).(3 - x ) = 0
=> - x + 5 = 0 hoặc 3 - x = 0
=> x = 5 hoặc x = 3
4) ( x - 12 ) - 15 = ( 20 - 7 ) - ( 18 + x )
x - 12 - 15 = 13 - 18 - x
x - 27 = - 5 - x
x + x = - 5 + 27
2x = 22
x = 11
5) x - ( 17 - 8 ) = 5 + ( 10 - 3x )
x - 9 = 5 + 10 - 3x
x + 3x = 15 + 9
4x = 24
x = 6
4) (x+1)+(x+2)+(x+3)+....+(x+30)=795
<=> (x+x+x+...+x)+(1+2+3+....+30)=795
<=> 30x+\(\frac{\left(30+1\right)\cdot30}{2}=795\)
<=> 30x+465=795
<=> 30x=330
<=> x=11
Vậy x=11
5) (x+1)+(x+3)+(x+5)+...+(x+99)=5100
<=> (x+x+x+...+x)+\(\frac{\left(99+1\right)\cdot50}{2}=5100\)
<=> 50x+2500=5100
<=> 50x=2600
<=> x=52
Vậy x=52
\(a.15-\left|x-3\right|=7\)
\(\Rightarrow\left|x-3\right|=8\)
\(\Rightarrow\orbr{\begin{cases}x-3=8\\x-3=-8\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=11\\x=-5\end{cases}}\)
\(b.x-\left(17-x\right)=x-10\)
\(\Rightarrow17-x=x-x+10\)
\(\Rightarrow17-x=10\)
\(\Rightarrow x=7\)