Tìm x biết:
\(\frac{x^2+1}{x-5}< 0\). mk cần gấp, ngày mai mk nộp bài rùi, help me
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\(8y+4y+2y+y-5y=28,6\)
\(\Rightarrow9y=28,6\)
\(\Rightarrow y=\frac{286}{90}\)
\(\left|x-2\right|+\left|x-3\right|+\left|x-4\right|=2\)
\(\le\left|x\right|-\left|2\right|+\left|x\right|-\left|3\right|+\left|x\right|-\left|4\right|\)
\(x-2+x-3+x-4=2\)
\(\Leftrightarrow x+x+x-2-3-4=2\)
\(\Leftrightarrow x^3-2-3-4=2\)
\(x^3=2+4+3+2\)
\(x^3=11\)
\(x=\sqrt[3]{11}\)
\(\hept{\begin{cases}x-1=0\\x-3=0\end{cases}}\hept{\begin{cases}x=0+1\\x=0+3\end{cases}}\hept{\begin{cases}x=1\\x=3\end{cases}}\)
t mk nhé
Có: \(\frac{1}{x\left(x+1\right)}\)= \(\frac{1}{x}-\frac{1}{x+1}\)
Mà \(\frac{1}{x\left(x+1\right)}=\frac{1}{x}+\frac{1}{2017}\)
=> \(\frac{1}{x}-\frac{1}{x+1}=\frac{1}{x}+\frac{1}{2017}\)
=> \(-\frac{1}{x+1}\)= \(\frac{1}{x}+\frac{1}{2017}-\frac{1}{x}\)
=> \(-\frac{1}{x+1}=\frac{1}{2017}\)
=> \(-1\cdot2017=\left(x+1\right)\cdot1\)
=> \(-2017=x+1\)
=> \(x=-2017-1\)
=> \(x=-2018\)
Vậy \(x=-2018\)
\(5\left(x+3\right)-2x\left(x+3\right)=0\)
<=> \(\left(5-2x\right)\left(x+3\right)=0\)
<=> \(\hept{\begin{cases}5-2x=0\\x+3=0\end{cases}}\)
<=> \(\hept{\begin{cases}x=\frac{5}{2}\\x=-3\end{cases}}\)
\(4x\left(x-2018\right)-x+2018=0\)
<=> \(4x\left(x-2018\right)-\left(x-2018\right)=0\)
<=> \(\left(4x-1\right)\left(x-2018\right)=0\)
<=> \(\hept{\begin{cases}4x-1=0\\x-2018=0\end{cases}}\)
<=> \(\hept{\begin{cases}x=\frac{1}{4}\\x=2018\end{cases}}\)
\(\left(x+1\right)^2-\left(x+1\right)=0\)
<=> \(\left(x+1\right)\left(x+1-1\right)=0\)
<=> \(\left(x+1\right).x=0\)
<=> \(\hept{\begin{cases}x=0\\x+1=0\end{cases}}\)
<=> \(\hept{\begin{cases}x=0\\x=-1\end{cases}}\)
học tốt
a) \(5\left(x+3\right)-2x\left(3+x\right)=0\)
\(5\left(x+3\right)+2x\left(x+3\right)=0\)
\(\left(x+3\right)\left(5+2x\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x+3=0\\5+2x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-3\\x=\frac{-5}{2}\end{cases}}\)
b) \(4x\left(x-2018\right)-x+2018=0\)
\(4x\left(x-2018\right)-\left(x-2018\right)=0\)
\(\left(x-2018\right)\left(4x-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-2018=0\\4x-1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=2018\\x=\frac{1}{4}\end{cases}}\)
c) \(\left(x+1\right)^2-\left(x+1\right)=0\)
\(\left(x+1\right)\left(x+1-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x+1=0\\x+1-1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-1\\x=0\end{cases}}\)
Ta có : \(x^2+1>0\)
Vậy để \(\frac{x^2+1}{x-5}< 0\) thì \(x-5< 0\Rightarrow x< 5\)