1.{10x-2y=-2
{-5x+y=1
2.{3x-y=4
{2x+y=6
3.{2x+3y=6
{x-2y=4 giai giup e a .giai chi tiet giup e.em dg can gap a.
1.{10x-2y=-2
{-5x+y=1
2.{3x-y=4
{2x+y=6
3.{2x+3y=6
{x-2y=4 giai giup e a .giai chi tiet giup e.em dg can gap a.
Đáp án:
\(\left\{ \begin{array}{l}
y = – \frac{2}{7}\\
x = \frac{{24}}{7}
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
1)\left\{ \begin{array}{l}
10x – 2y = – 2\\
y = 1 + 5x
\end{array} \right.\\
\to \left\{ \begin{array}{l}
10x – 2\left( {1 + 5x} \right) = – 2\\
y = 1 + 5x
\end{array} \right.\\
\to \left\{ \begin{array}{l}
10x – 2 – 10x = – 2\\
y = 1 + 5x
\end{array} \right.\\
\to \left\{ \begin{array}{l}
0x = 0\left( {ld} \right)\\
y = 1 + 5x
\end{array} \right.
\end{array}\)
⇒ Hệ phương trình có vô số nghiệm
\(\begin{array}{l}
2)\left\{ \begin{array}{l}
3x – y = 4\\
2x + y = 6
\end{array} \right.\\
\to \left\{ \begin{array}{l}
3x + 2x = 4 + 6\\
y = 3x – 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
5x = 10\\
y = 3x – 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 2\\
y = 3x – 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 2\\
y = 2
\end{array} \right.\\
3)\left\{ \begin{array}{l}
2x + 3y = 6\\
x – 2y = 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 2y + 4\\
2\left( {2y + 4} \right) + 3y = 6
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 2y + 4\\
4y + 8 + 3y = 6
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 2y + 4\\
7y = – 2
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = – \frac{2}{7}\\
x = \frac{{24}}{7}
\end{array} \right.
\end{array}\)