Ai giúp em 10 với 8 được không ạ
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8.
Gọi \(A\left(x_0;y_0\right)\) là điểm cố định mà đt luôn đi qua với mọi m
\(\Leftrightarrow mx_0+2y_0-3my_0+m-1=0\\ \Leftrightarrow m\left(x_0-3y_0+1\right)+\left(2y_0-1\right)=0\\ \Leftrightarrow\left\{{}\begin{matrix}x_0-3y_0+1=0\\2y_0-1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x_0=\dfrac{1}{2}\\y_0=\dfrac{1}{2}\end{matrix}\right.\Leftrightarrow A\left(\dfrac{1}{2};\dfrac{1}{2}\right)\)
Vậy đt luôn đi qua \(A\left(\dfrac{1}{2};\dfrac{1}{2}\right)\) với mọi m
9.
PT giao Ox là \(y=0\Leftrightarrow mx+m-1=0\Leftrightarrow x=\dfrac{1-m}{m}\Leftrightarrow A\left(\dfrac{1-m}{m};0\right)\Leftrightarrow OA=\left|\dfrac{1-m}{m}\right|\)
PT giao Oy là \(x=0\Leftrightarrow\left(2-3m\right)y+m-1=0\Leftrightarrow y=\dfrac{1-m}{2-3m}\Leftrightarrow B\left(0;\dfrac{1-m}{2-3m}\right)\Leftrightarrow OB=\left|\dfrac{1-m}{2-3m}\right|\)
Để \(\Delta OAB\) cân thì \(OA=OB\Leftrightarrow\left|\dfrac{1-m}{m}\right|=\left|\dfrac{1-m}{2-3m}\right|\)
\(\Leftrightarrow\left|m\right|=\left|2-3m\right|\Leftrightarrow\left[{}\begin{matrix}m=2-3m\\m=3m-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}m=\dfrac{1}{2}\\m=1\end{matrix}\right.\)
Vậy \(\left[{}\begin{matrix}m=\dfrac{1}{2}\\m=1\end{matrix}\right.\) thỏa mãn đề
10: Ta có: \(\left(\dfrac{x+1}{x}\right)^2:\left[\dfrac{x^2+1}{x^2}+\dfrac{2}{x+1}\cdot\left(\dfrac{1}{x+1}+1\right)\right]\)
\(=\dfrac{\left(x+1\right)^2}{x^2}:\left(\dfrac{x^2+1}{x^2}+\dfrac{2\cdot\left(x+2\right)}{\left(x+1\right)^2}\right)\)
\(=\dfrac{\left(x+1\right)^2}{x^2}:\dfrac{\left(x^2+1\right)\left(x^2+2x+1\right)+2x^2\left(x+2\right)}{x^2\left(x+1\right)^2}\)
\(=\dfrac{\left(x+1\right)^2}{x^2}\cdot\dfrac{x^2\left(x+1\right)^2}{x^4+2x^3+x^2+x^2+2x+1+2x^3+4x^2}\)
\(=\dfrac{\left(x+1\right)^4}{x^4+4x^3+6x^2+2x+1}\)
9, = \(\left(x^2\right)^2-\left(\dfrac{2}{5}y\right)^2=x^4-\dfrac{4}{25}y^2\)
10, = \(\left(\dfrac{x}{2}\right)^2-y^2=\dfrac{x^2}{4}-y^2\)
\(\left(1-\frac{3}{4}\right)\left(1-\frac{3}{7}\right)\cdot\cdot\cdot\left(1-\frac{3}{100}\right)\)
\(=\frac{1}{4}\cdot\frac{4}{7}\cdot\frac{7}{10}\cdot\cdot\cdot\frac{97}{100}\)
\(=\frac{1.4.7.10...97}{4.7.10.13...100}\)
\(=\frac{1}{100}\)
Câu 7:
Thay x=0 và y=9 vào (d), ta được:
-2m-3=9
hay m=-6
8, \(\left(\frac{2}{\left(x+1\right)^3}\left(\frac{1}{x}+1\right)+\frac{1}{x^2+2x+1}\left(\frac{1}{x^2}+1\right)\right):\frac{x-1}{x^3}\)Với \(x\ne0;\pm1\)
\(=\left(\frac{2}{\left(x+1\right)^3}\left(\frac{x+1}{x}\right)+\frac{1}{\left(x+1\right)^2}\left(\frac{x^2+1}{x^2}\right)\right):\frac{x-1}{x^3}\)
\(=\left(\frac{2\left(x+1\right)}{x\left(x+1\right)^3}+\frac{x^2+1}{x^2\left(x+1\right)^2}\right):\frac{x-1}{x^3}=\left(\frac{2x\left(x+1\right)+\left(x+1\right)\left(x^2+1\right)}{x^2\left(x+1\right)^3}\right):\frac{x-1}{x^3}\)
\(=\left(\frac{\left(x+1\right)^3}{x^2\left(x+1\right)^3}\right):\frac{x-1}{x^3}=\frac{1}{x^2}:\frac{x-1}{x^3}=\frac{x}{x-1}\)
10, \(\left(\frac{x+1}{x}\right)^2:\left(\frac{x^2+1}{x^2}+\frac{2}{x+1}\left(\frac{1}{x+1}+1\right)\right)\)
\(=\left(\frac{x+1}{x}\right)^2:\left(\frac{x^2+1}{x^2}+\frac{2}{x+1}\left(\frac{x+2}{x+1}\right)\right)\)
\(=\left(\frac{x+1}{x}\right)^2:\left(\frac{x^2+1}{x^2}+\frac{2\left(x+2\right)}{\left(x+1\right)^2}\right)=\left(\frac{x+1}{x}\right)^2:\left(\frac{\left(x^2+1\right)\left(x+1\right)^2+2x^2\left(x+2\right)}{x^2\left(x+1\right)^2}\right)\)
\(=\left(\frac{x+1}{x}\right)^2:\left(\frac{\left(x^2+1\right)\left(x^2+2x+1\right)+2x^3+4x^2}{x^2\left(x+1\right)^2}\right)\)
\(=\left(\frac{x+1}{x}\right)^2:\left(\frac{x^4+2x^3+x^2+x^2+2x+1+2x^3+4x^2}{x^2\left(x+1\right)^2}\right)\)
\(=\left(\frac{x+1}{x}\right)^2:\left(\frac{x^4+4x^3+6x^2+2x+1}{x^2\left(x+1\right)^2}\right)=\frac{\left(x+1\right)^4}{x^4+4x^3+6x^2+2x+1}\)