a, \(\left\{{}\begin{matrix}8x-7y=5\\12x+13y=-8\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}24x-21y=15\\24x+26y=-16\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}8x-7y=5\\47y=-31\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{9}{188}\\y=-\dfrac{31}{47}\end{matrix}\right.\)
b, \(\left\{{}\begin{matrix}3\sqrt{5}x+4y=15-2\sqrt{7}\\-2\sqrt{5}x+8\sqrt{7}y=18\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}6\sqrt{5}x+8y=30-4\sqrt{7}\\-6\sqrt{5}x+24\sqrt{7}y=54\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}3\sqrt{5}x+4y=15-2\sqrt{7}\\y\left(24\sqrt{7}+8\right)=84-4\sqrt{7}\end{matrix}\right.\) (tự làm tiếp)
Đúng 2
Bình luận (0)