Biết hệ pt 4/x-3+1/y+1=5 5/x-3-2/y+1=3 có nghiệm (x0,y0). Tính 2x0+3x0
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Đáp án:
$\begin{array}{l}
\left\{ \begin{array}{l}
\frac{4}{{x - 3}} + \frac{1}{{y + 1}} = 5\\
\frac{5}{{x - 3}} - \frac{2}{{y + 1}} = 3
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
4.\frac{1}{{x - 3}} + \frac{1}{{y + 1}} = 5\\
5.\frac{1}{{x - 3}} - 2.\frac{1}{{y + 1}} = 3
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
\frac{1}{{x - 3}} = 1\\
\frac{1}{{y + 1}} = 1
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
x - 3 = 1\\
y + 1 = 1
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
x = 4\\
y = 0
\end{array} \right.\\
\Rightarrow 2{x_0} + 3{x_0} = 8
\end{array}$
