\(\frac{1}{2\left(x-1\right)}+\frac{3}{x^2-1}=\frac{1}{4}\)
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15 tháng 4 2020

Đây là lớp 8 nha các b giúp mk với

Do mk viết nhầm

NV
3 tháng 11 2019

a/ ĐKXĐ: ...

\(\Leftrightarrow\frac{x+1}{2\left(x^2-1\right)}+\frac{3}{x^2-1}=\frac{1}{4}\)

\(\Leftrightarrow\frac{x+7}{x^2-1}=\frac{1}{2}\Leftrightarrow2x+14=x^2-1\)

\(\Leftrightarrow x^2-2x-15=0\Rightarrow\left[{}\begin{matrix}x=5\\x=-3\end{matrix}\right.\)

b/ ĐKXĐ: ...

Đặt \(\frac{x-1}{x}=a\)

\(a-\frac{3}{2a}=-\frac{5}{2}\Leftrightarrow2a^2+5a-3=0\)

\(\Rightarrow\left[{}\begin{matrix}a=-3\\a=\frac{1}{2}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\frac{x-1}{x}=-3\\\frac{x-1}{x}=\frac{1}{2}\end{matrix}\right.\)

c/ ĐKXĐ: ...

\(\Leftrightarrow\frac{\left(x+2\right)\left(2x+3\right)-\left(2x-3\right)}{4x^2-9}=\frac{4x^2-9-\left(2x^2-x-4\right)}{4x^2-9}\)

\(\Leftrightarrow2x^2+5x+9=2x^2+x-5\)

\(\Leftrightarrow4x=-14\Rightarrow x=-\frac{7}{2}\)

giải các hệ BPT sau: a) \(\left\{{}\begin{matrix}5x-24x+5\\5x-4< x+2\end{matrix}\right.\) b) \(\left\{{}\begin{matrix}2x+1>3x+4\\5x+3\ge8x-9\end{matrix}\right.\) c) \(\left\{{}\begin{matrix}\frac{5x+2}{3}\ge4-x\\\frac{6-5x}{13}< 3x+1\end{matrix}\right.\) d) \(\left\{{}\begin{matrix}\frac{4x-5}{7}< x+3\\\frac{3x+8}{4}>2x-5\end{matrix}\right.\) e) \(\left\{{}\begin{matrix}6x+\frac{5}{7}< 4x+7\\\frac{8x+3}{2}< 2x+5\end{matrix}\right.\) f) \(\left\{{}\begin{matrix}15x-2>2x+\frac{1}{3}\\2\left(x-4\right)< \frac{3x-14}{2}\end{matrix}\right.\) g) \(\left\{{}\begin{matrix}x-1\le2x-3\\3x< x+5\\5-3x\le2x-6\end{matrix}\right.\) h) \(\left\{{}\begin{matrix}2x+\frac{3}{5}>\frac{3\left(2x-7\right)}{3}\\x-\frac{1}{2}< \frac{5\left(3x-1\right)}{2}\end{matrix}\right.\) j)...
Đọc tiếp

giải các hệ BPT sau:

a) \(\left\{{}\begin{matrix}5x-2>4x+5\\5x-4< x+2\end{matrix}\right.\)

b) \(\left\{{}\begin{matrix}2x+1>3x+4\\5x+3\ge8x-9\end{matrix}\right.\)

c) \(\left\{{}\begin{matrix}\frac{5x+2}{3}\ge4-x\\\frac{6-5x}{13}< 3x+1\end{matrix}\right.\)

d) \(\left\{{}\begin{matrix}\frac{4x-5}{7}< x+3\\\frac{3x+8}{4}>2x-5\end{matrix}\right.\)

e) \(\left\{{}\begin{matrix}6x+\frac{5}{7}< 4x+7\\\frac{8x+3}{2}< 2x+5\end{matrix}\right.\)

f) \(\left\{{}\begin{matrix}15x-2>2x+\frac{1}{3}\\2\left(x-4\right)< \frac{3x-14}{2}\end{matrix}\right.\)

g) \(\left\{{}\begin{matrix}x-1\le2x-3\\3x< x+5\\5-3x\le2x-6\end{matrix}\right.\)

h) \(\left\{{}\begin{matrix}2x+\frac{3}{5}>\frac{3\left(2x-7\right)}{3}\\x-\frac{1}{2}< \frac{5\left(3x-1\right)}{2}\end{matrix}\right.\)

j) \(\left\{{}\begin{matrix}\frac{3x+1}{2}-\frac{3-x}{3}\le\frac{x+1}{4}-\frac{2x-1}{3}\\3-\frac{2x+1}{5}>x+\frac{4}{3}\end{matrix}\right.\)

3
25 tháng 3 2020
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25 tháng 3 2020
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11 tháng 1 2020
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