Đáp án:
c) \(\left\{ \begin{array}{l}
x = 5\\
y = 8
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
a)\left\{ \begin{array}{l}
- 9{x^3} - 6{y^2} = 18\\
8{x^3} + 6{y^2} = - 10
\end{array} \right.\\
\to \left\{ \begin{array}{l}
- {x^3} = 8\\
8{x^3} + 6{y^2} = - 10
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = - 2\\
{y^2} = 9
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = - 2\\
\left[ \begin{array}{l}
y = 3\\
y = - 3
\end{array} \right.
\end{array} \right.\\
b)DK:x \ge 0\\
\left\{ \begin{array}{l}
4\sqrt x - 3\left| {y - 1} \right| = 4\\
6\sqrt x + 3\left| {y - 1} \right| = 6
\end{array} \right.\\
\to \left\{ \begin{array}{l}
10\sqrt x = 10\\
4\sqrt x - 3\left| {y - 1} \right| = 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 1\\
3\left| {y - 1} \right| = 0
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 1\\
y - 1 = 0
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 1\\
y = 1
\end{array} \right.\\
c)DK:x \ge 1;y \ge - 1\\
\left\{ \begin{array}{l}
18\sqrt {x - 1} - 2\sqrt {y + 1} = 30\\
5\sqrt {x - 1} - 2\sqrt {y + 1} = 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
13\sqrt {x - 1} = 26\\
5\sqrt {x - 1} - 2\sqrt {y + 1} = 4
\end{array} \right.\\
\to \left\{ \begin{array}{l}
\sqrt {x - 1} = 2\\
2\sqrt {y + 1} = 6
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x - 1 = 4\\
y + 1 = 9
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 5\\
y = 8
\end{array} \right.
\end{array}\)
