x.(10-x).(5x-25)
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TT
19 tháng 12 2020
ĐKXĐ : \(x\ne\pm5\)
\(C=\dfrac{\left(x+2\right)\left(x-2\right)}{x^2-25}.\dfrac{x^2-25}{x^2+10}=\dfrac{x^2-4}{x^2+10}\)
\(C=2\Leftrightarrow x^2-4=2x^2+20\Leftrightarrow x^2=-24\left(vô-lí\right)\)
MT
1
12 tháng 10 2020
\(A=\left(\frac{x}{25+5x}+\frac{5x+50}{x^2+5x}-\frac{10-2x}{x}\right)\div\frac{3x+15}{7}\)
ĐK : \(\hept{\begin{cases}x\ne0\\x\ne-5\end{cases}}\)
\(=\left(\frac{x}{5\left(x+5\right)}+\frac{5\left(x+10\right)}{x\left(x+5\right)}-\frac{2\left(5-x\right)}{x}\right)\div\frac{3\left(x+5\right)}{7}\)
\(=\left(\frac{x^2}{5x\left(x+5\right)}+\frac{5\cdot5\cdot\left(x+10\right)}{5x\left(x+5\right)}-\frac{2\left(5-x\right)\cdot5\left(x+5\right)}{5x\left(x+5\right)}\right)\div\frac{3\left(x+5\right)}{7}\)
\(=\left(\frac{x^2}{5x\left(x+5\right)}+\frac{25x+250}{5x\left(x+5\right)}-\frac{10\left(25-x^2\right)}{5x\left(x+5\right)}\right)\div\frac{3\left(x+5\right)}{7}\)
\(=\left(\frac{x^2+25x+250-250+10x^2}{5x\left(x+5\right)}\right)\div\frac{3\left(x+5\right)}{7}\)
\(=\frac{11x^2+25x}{5x\left(x+5\right)}\times\frac{7}{3\left(x+5\right)}\)
\(=\frac{77x^2+175x}{15x\left(x+5\right)^2}\)
\(=\frac{77x^2+175x}{15x\left(x^2+10x+25\right)}=\frac{77x^2+175x}{15x^3+150x^2+375x}\)
\(=\frac{77x+175}{15x^2+150x+375}\)
VD
18 tháng 3 2022
\(a,2x-5=-x+4\\ \Leftrightarrow3x=9\\ \Leftrightarrow x=3\\ b,\left(4x-10\right)\left(25+5x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}4x-10=0\\25+5x=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-5\end{matrix}\right.\\ c,\dfrac{x}{3}-\dfrac{2x+1}{2}=\dfrac{x}{6}-x\\ \Leftrightarrow\dfrac{2x}{6}-\dfrac{3\left(2x+1\right)}{6}-\dfrac{x}{6}+\dfrac{6x}{6}=0\\ \Leftrightarrow2x-6x-3-x+6x=0\\ \Leftrightarrow x-3=0\\ \Leftrightarrow x=3\)
d, ĐKXĐ:\(x\ne-2,x\ne3\)
\(1+\dfrac{x}{3-x}=\dfrac{5x}{\left(x+2\right)\left(3-x\right)}+\dfrac{2}{x+2}\\ \Leftrightarrow\dfrac{\left(x+2\right)\left(3-x\right)}{\left(x+2\right)\left(3-x\right)}+\dfrac{x\left(x+2\right)}{\left(x+2\right)\left(3-x\right)}-\dfrac{5x}{\left(x+2\right)\left(3-x\right)}-\dfrac{2\left(3-x\right)}{\left(x+2\right)\left(3-x\right)}=0\\ \Leftrightarrow\dfrac{-x^2+x+6}{\left(x+2\right)\left(3-x\right)}+\dfrac{x^2+2x}{\left(x+2\right)\left(3-x\right)}-\dfrac{5x}{\left(x+2\right)\left(3-x\right)}-\dfrac{6-2x}{\left(x+2\right)\left(3-x\right)}=0\)
\(\Leftrightarrow\dfrac{-x^2+x+6+x^2+2x-5x-6+2x}{\left(x+2\right)\left(3-x\right)}=0\\ \Rightarrow0=0\left(luôn.đúng\right)\)
NL
2
ND
1
29 tháng 3 2018
a)\(P=\dfrac{x^2}{5x+25}+\dfrac{2x-10}{x}+\dfrac{50+5x}{x^2+5x}\left(đkxđ:x\ne0;-5\right)\)
\(P=\dfrac{x^2}{5\left(x+5\right)}+\dfrac{2\left(x-5\right)}{x}+\dfrac{50+5x}{x\left(x+5\right)}\)
\(P=\dfrac{x^3+10\left(x+5\right)\left(x-5\right)+5\left(50+5x\right)}{5x\left(x+5\right)}\)
\(P=\dfrac{x^3+10x^2-250+250+25x}{5x\left(x+5\right)}\)
\(P=\dfrac{x\left(x+5\right)^2}{5x\left(x+5\right)}\)
\(P=\dfrac{x+5}{5}\)
b)P âm\(\Leftrightarrow x+5< 0\Leftrightarrow x< -5\)
22 tháng 7 2018
\(175-5\times\left(x-10\right)=25\)
\(\Rightarrow5\times\left(x-10\right)=175-25\)
\(\Rightarrow5\times\left(x-10\right)=150\)
\(\Rightarrow x-10=150:5\)
\(\Rightarrow x-10=30\)
\(\Rightarrow x=30+10\)
\(\Rightarrow x=40\)
Học tốt #
22 tháng 7 2018
\(175-5\left(x-10\right)=25\)
\(\Leftrightarrow5\left(x-10\right)=150\)
\(\Leftrightarrow x-10=30\)
\(\Leftrightarrow x=40\)
hok tốt nhé!
17 tháng 12 2017
\(\frac{x^2}{5x+25}-\frac{10-2x}{x}+\frac{5x+50}{5x+x^2}=\frac{x^2}{5\left(x+5\right)}-\frac{10-2x}{x}+\frac{5x+50}{x\left(x+5\right)}\)
\(=\frac{x^3}{5x\left(x+5\right)}-\frac{5\left(x+5\right)\left(10-2x\right)}{5x\left(x+5\right)}+\frac{5\left(5x+50\right)}{5x\left(x+5\right)}\)
\(=\frac{x^3+10x^2+25x}{5x\left(x+5\right)}=\frac{x\left(x+5\right)^2}{5x\left(x+5\right)}=\frac{x+5}{5}\)
PH
1
21 tháng 9 2017
a ) \(\left(x+4\right)^2+\left(1-x\right)\left(1+x\right)=7\)
\(\Leftrightarrow x^2+8x+16+1^2-x^2=7\)
\(\Leftrightarrow8x+17=7\)
\(\Leftrightarrow8x+10=0\)
\(\Rightarrow x=-\dfrac{10}{8}\)
=(10x-x^2)(5x-25)
=50x^2-250x-5x^3+25x^2
=-5x^3+75x^2-250x
`@` `\text {Ans}`
`\downarrow`
`x(10-x)(5x-25)`
`= (10x-x^2)(5x-25)`
`= 10x(5x-25) - x^2(5x-25)`
`= 50x^2-250x - 5x^3 + 25x^2`
`= -5x^3+75x^2-250x`