Tìm x :
1) \(\frac{-15}{12}\)x \(+\) \(\frac{3}{2}\)= \(\frac{1}{3}\)x \(-\) \(\frac{1}{2}\)
2) \(\frac{X+2}{0,5}=\frac{2x+1}{2}\)
3) \(\left(x+3\right).\left(x-7\right)=0\)
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1/3 - 5/6 ( x + 1 ) = 0,5
1/3 - 5/6 ( x + 1 ) = 1/2
5/6 ( x + 1 ) = 1/3 - 1/2
5/6 ( x + 1 ) = -1/6
x + 1 = -1/6 : 5/6
x +1 = -1/5
x = -1/5 - 1
x = -6/5
\(\frac{1}{3}-\frac{5}{6}.\left(x+1\right)=0.5\)
\(\frac{5}{6}.\left(x+1\right)=\frac{1}{3}-0.5\)
\(\frac{5}{6}.\left(x+1\right)=\frac{-1}{6}\)
\(x+1=\frac{-1}{6}:\frac{5}{6}\)
\(x+1=\frac{-1}{5}\)
\(x=\frac{-1}{5}-1\)
\(x=\frac{-6}{5}\)
Vậy \(x=\frac{-6}{5}\)
CHÚC BẠN HỌC TỐT
\(C=\frac{a}{b+c}+\frac{b}{a+c}+\frac{c}{a+b}\)
\(>\frac{a}{a+b+c}+\frac{b}{a+b+c}+\frac{c}{a+b+c}=1\)
\(D< \frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2016.2017}\)
\(\Rightarrow D< 1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2016}-\frac{1}{2017}\)
\(\Rightarrow D< 1-\frac{1}{2017}< 1\)
Vậy C > D
Ta có: x+3z+x+2y=8+9
⇒2x+2y+3z=17
⇒2x+2y+2z+z=17
⇒2(x+y+z)=17−z
Mà x+y+z có GTLN
⇒17−z cũng có GTLN
Mà z≥0⇒−z≤0
⇒17−z≤17
⇒17−z đạt GTLN là 17 tại z=0
+) x+3z=8
Thay z=0
⇒x+0=8
⇒x=8
+) x+2y=9
Thay x=8
⇒8+2y=9
⇒2y=1
⇒y=12
Vậy x=8;y=12;z=0
\(\frac{-15}{12}x+\frac{3}{2}=\frac{1}{3}x-\frac{1}{2}\)
\(\Leftrightarrow\frac{-15}{12}x=\frac{1}{3}x-\frac{1}{2}-\frac{3}{2}\)
\(\Leftrightarrow\frac{1}{3}x-\frac{1}{2}-\frac{3}{2}=\frac{-15}{12}x\)
\(\Leftrightarrow\frac{1}{3}x-\left(\frac{1}{2}+\frac{3}{2}\right)=\frac{-15}{12}x\)
\(\Leftrightarrow2=\frac{1}{3}x-\frac{-5}{4}x\)
\(\Leftrightarrow x\left(\frac{1}{3}+\frac{5}{4}\right)=2\)
\(\Leftrightarrow\frac{19}{12}x=2\)
\(\Leftrightarrow x=2\times\frac{12}{19}\)
\(\Leftrightarrow x=\frac{24}{19}\)
\(\frac{x+2}{0,5}=\frac{2x+1}{2}\)
\(\Leftrightarrow2\left(x+2\right)=\left(2x+1\right)\times\frac{1}{2}\)
\(\Leftrightarrow2x+4=x+\frac{1}{2}\)
\(\Leftrightarrow2x+4-x=\frac{1}{2}\)
\(\Leftrightarrow2x-x=\frac{1}{2}-4\)
\(\Leftrightarrow x=-3,5\)
\(\Leftrightarrow x=-3,5\)