3x-17=31
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\(\Leftrightarrow\frac{3x+1}{17}+\frac{3x+1}{19}+\frac{3x+1}{23}-\frac{3x+1}{29}-\frac{3x+1}{31}=0\)
\(\Leftrightarrow\left(3x+1\right)\left(\frac{1}{17}+\frac{1}{19}+\frac{1}{23}-\frac{1}{29}-\frac{1}{31}\right)=0\)
\(\Leftrightarrow3x+1=0\) ( vì \(\frac{1}{17}+\frac{1}{19}+\frac{1}{23}-\frac{1}{29}-\frac{1}{31}\ne0\))
\(\Leftrightarrow3x=-1\)
\(\Leftrightarrow x=-\frac{1}{3}\)
\(\frac{3x+1}{17}+\frac{3x+1}{19}+\frac{3x+1}{23}=\frac{3x+1}{29}+\frac{3x+1}{31}\)
\(\Rightarrow\frac{3x+1}{17}+\frac{3x+1}{19}+\frac{3x+1}{23}-\frac{3x+1}{29}-\frac{3x+1}{31}=0\)
\(\Rightarrow\left(3x+1\right)\left(\frac{1}{17}+\frac{1}{19}+\frac{1}{23}-\frac{1}{29}-\frac{1}{31}\right)=0\)
Mà \(\frac{1}{17}+\frac{1}{19}+\frac{1}{23}-\frac{1}{29}-\frac{1}{31}\ne0\)
\(\Rightarrow3x+1=0\)
\(\Rightarrow x=-\frac{1}{3}\)
a) 2x - 31 + 42 = - 3x - 45
2x + 11 = - 3x - 45
2x + 3x = - 45 - 11
5x = - 56
x = - 56/5
b) - 25 + 2x = 15 + 17 - x
2x + x = 32 + 25
3x = 57
x = 19
1) 3x-(4+2x)=11
3x - 4 - 2x = 11
3x - 2x = 11+4
x = 15
Vậy x = 15.
2) 4x+5=11+2x
4x - 2x = 11 - 5
2x = 6
x = 6 : 2
x = 3
Vậy x = 3.
3) 7x-17=31+x
7x - x = 31 + 17
6x = 48
x = 48 : 6
x = 8
Vậy x = 8
# HOK TỐT #
\(3x-\left(4+2x\right)=11\)
\(3x-4-2x=11\)
\(x-15=0\)
\(x=15\)
\(4x+5=11+2x\)
\(2x-6=0\)
\(2x=6\)
\(x=3\)
Bn lm phần c đi , cố lên !
\(3x+12=36\)
\(\Leftrightarrow3x=36-12\)
\(\Leftrightarrow3x=24\)
\(\Leftrightarrow x=24\div3\)
\(\Leftrightarrow x=8\)
\(4x+28=134\)
\(\Leftrightarrow4x=134-28\)
\(\Leftrightarrow4x=106\)
\(\Leftrightarrow x=106\div4\)
\(\Leftrightarrow x=\frac{53}{2}\)
\(5x-22=-17\)
\(\Leftrightarrow5x=22-17\)
\(\Leftrightarrow5x=5\)
\(\Leftrightarrow x=5\div5\)
\(\Leftrightarrow x=1\)
3x + 12 = 36
3x = 36 - 12
3x = 24
x = 8
4x + 28 = 134
4x = 134 - 28
4x = 106
x = 106 : 4
x = 26 , 5
5x - 22 = -17
5x = -17 + 22
5x = 5
x = 1
3x - 184 = -49
3x = -49 + 184
3x = 135
x = 135 : 3 = 45
4x + 12 = 56
4x = 56 - 12
4x = 44
x = 11
3x - 127 = - 22
3x = -22 + 127
3x = 105
x = 105 : 3 = 35
3x + 22 = 124
3x = 124 - 22 = 102
x = 102 : 3
x = 34
4x - 9 = 31
4x = 31 + 9 = 40
x = 40 : 4= 10
5x - 211 = -31
5x = -31 + 211
5x = 180
x = 180 : 5
x = 36
\(\left|x-11\right|=7\)
\(\Leftrightarrow\orbr{\begin{cases}x-11=7\\x-11=-7\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=18\\x=4\end{cases}}\)
d,\(\left(3x-12\right)\left(x+31\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x-12=0\\x+31=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=4\\x=-31\end{cases}}\)
=\(\dfrac{11}{31}\)*\(\left(\dfrac{-2}{17}-\dfrac{-9}{17}\right)\)+\(\dfrac{7}{31}\)*\(\dfrac{-20}{17}\)
=\(\dfrac{11}{31}\)*\(\dfrac{-7}{17}\)+\(\dfrac{7}{31}\)*\(\dfrac{-20}{17}\)
=\(\dfrac{-77}{512}\)+\(\dfrac{-140}{512}\)
=\(\dfrac{-217}{512}\)
3x=31+17=48
x=48:3=16
3x=48
x=16