Giải hệ phương trình:
1. $\left \{ {{x+|y-12|} \atop {-x+2y=27}} \right.$
2. $\left \{ {{\frac{3}{x+1}}-\frac{4}{y-2}+1=0 \atop {x+y-1=2(x+1)(y-2)}} \right.$
Giải hệ phương trình:
1. $\left \{ {{x+|y-12|} \atop {-x+2y=27}} \right.$
2. $\left \{ {{\frac{3}{x+1}}-\frac{4}{y-2}+1=0 \atop {x+y-1=2(x+1)(y-2)}} \right.$
Đáp án:
2) y=3; x=0
Giải thích các bước giải:
\(\begin{array}{l}
2)DK:x \ne – 1;y \ne 2\\
\left\{ \begin{array}{l}
\dfrac{{3\left( {y – 2} \right) – 4\left( {x + 1} \right) + \left( {x + 1} \right)\left( {y – 2} \right)}}{{\left( {x + 1} \right)\left( {y – 2} \right)}} = 0\\
x + y – 1 = 2\left( {x + 1} \right)\left( {y – 2} \right)
\end{array} \right.\\
\to \left\{ \begin{array}{l}
3y – 6 – 4x – 4 + xy – 2x + y – 2 = 0\\
x + y – 1 = 2\left( {xy – 2x + y – 2} \right)
\end{array} \right.\\
\to \left\{ \begin{array}{l}
– 6x + 4y + xy = 12\\
5x – y – 2xy = – 3
\end{array} \right.\\
\to \left\{ \begin{array}{l}
– 12x + 8y + 2xy = 24\\
5x – y – 2xy = – 3
\end{array} \right.\\
\to \left\{ \begin{array}{l}
– 7x + 7y = 21\\
5x – y – 2xy = – 3
\end{array} \right.\\
\to \left\{ \begin{array}{l}
– x + y = 3\\
5x – y – 2xy = – 3
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = y – 3\\
5\left( {y – 3} \right) – y – 2\left( {y – 3} \right).y = – 3\left( 1 \right)
\end{array} \right.\\
\left( 1 \right) \to 5y – 15 – y – 2\left( {{y^2} – 3y} \right) = – 3\\
\to – 2{y^2} + 10y – 12 = 0\\
\to \left[ \begin{array}{l}
y = 3\\
y = 2\left( l \right)
\end{array} \right. \to x = 0
\end{array}\)
( câu 1 thiếu dấu “=” bạn )