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2.(x-5)-3.(x+6)=10+x
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LH
22 tháng 10 2017
\(2(x-5)-3(x+6)=10+x\)
\(\Rightarrow2x-10-3x+18=10x\)
\(\Rightarrow2x-10-3x-18=10+x\)
\(\Rightarrow-x-28=10+x\)
\(\Rightarrow-x-x=10+28\)
\(\Rightarrow-2x=38\)
\(\Rightarrow x=-19\)
Vậy ..
22 tháng 10 2017
\(2\left(x-5\right)-\left(3x+6\right)=10+x\)
\(\Rightarrow2x-10-3x-18=10+x\)
\(\Rightarrow-x-28=10+x\)
\(\Rightarrow-x=38+x\)
\(\Rightarrow-2x=38\Leftrightarrow x=-19\)
J
0
TN
29 tháng 4 2017
\(4x-3-x-5-=x+2-2x+2.10\)
\(3x-8=x+2-2x+20\)
\(3x=x+10-2x+20\)
\(3x=-x+30\)
\(4x=30\)
\(x=\frac{30}{4}=7,5\)
18 tháng 6 2016
a) \(\Leftrightarrow\left|2x-3\right|=\frac{1}{4}\Leftrightarrow\orbr{\begin{cases}x\ge\frac{3}{2}\mid:2x-3=\frac{1}{4}\Rightarrow2x=\frac{13}{4}\Rightarrow x=\frac{13}{8}\left(TM\right)\\x< \frac{3}{2}\mid:3-2x=\frac{1}{4}\Rightarrow2x=\frac{11}{4}\Rightarrow x=\frac{11}{8}\left(TM\right)\end{cases}.}\)
b) \(\Leftrightarrow\left|x-1\right|=\frac{3}{4}\Leftrightarrow\orbr{\begin{cases}x\ge1\mid:x-1=\frac{3}{4}\Rightarrow x=\frac{7}{4}\left(TM\right)\\x< 1\mid:1-x=\frac{3}{4}=>x=\frac{1}{4}\left(TM\right)\end{cases}}\)
c) \(\frac{3}{5\left(x-\frac{5}{6}\right)}-\frac{1}{2\left(\frac{3}{2}-1\right)}=-\frac{1}{4}\Leftrightarrow\frac{3}{\frac{5\left(6x-5\right)}{6}}-\frac{1}{2\cdot\frac{1}{2}}=-\frac{1}{4}\Leftrightarrow\frac{18}{5\left(6x-5\right)}=-\frac{1}{4}+1\)
\(\Leftrightarrow\frac{18}{5\left(6x-5\right)}=\frac{3}{4}\Leftrightarrow6x-5=\frac{24}{5}\Leftrightarrow6x=\frac{49}{5}\Leftrightarrow x=\frac{49}{30}\)
d) \(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=\frac{2015}{2016}\)
\(\Leftrightarrow\frac{2}{2\cdot3}+\frac{2}{3\cdot4}+\frac{2}{4\cdot5}+...+\frac{2}{x\left(x+1\right)}=\frac{2015}{2016}\)
\(\Leftrightarrow2\cdot\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{2015}{2016}\)
\(\Leftrightarrow2\left(\frac{1}{2}-\frac{1}{x+1}\right)=\frac{2015}{2016}\Leftrightarrow2\cdot\frac{x+1-2}{2\left(x+1\right)}=\frac{2015}{2016}\Leftrightarrow\frac{x-1}{x+1}=\frac{2015}{2016}\)
\(\Leftrightarrow2016x-2016=2015x+2015\Leftrightarrow x=2015+2016=4031\)
Vậy x = 4031.
25 tháng 12 2015
a) 6 + 2x = 12 +(-5)
2x = 7 -6
x = 1/2
b) -90 - |x| -10 + 100 = 0
- |x| =0
x =0
DT
0
NV
0
3(x - 5) - 3(x + 6) = 10 + x
\(\Rightarrow\) 3x - 15 - (3x + 18) = 10 + x
\(\Rightarrow\) 3x - 15 - 3x - 18 = 10 + x
\(\Rightarrow\) -3 = 10 + x
\(\Rightarrow\) x = -13