\(\left\{{}\begin{matrix}3x-2y=-12\\2x+5y=11\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}3x-2y=-12\\3x+\dfrac{15}{2}x=\dfrac{33}{2}\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}3x-2y=-12\\-\dfrac{19}{2}y=-\dfrac{57}{2}`\end{matrix}\right.\)
⇔\(\left\{{}\begin{matrix}x=-2\\y=3\end{matrix}\right.\)
Vậy HPT có nghiệm (x;y) =(-2;3)
2)A= \(\left(\dfrac{a+\sqrt{a}}{\sqrt{a}+1}+\dfrac{a-4\sqrt{a}+4}{\sqrt{a}-2}\right).\dfrac{3}{\sqrt{a}-1}\)
A= \(\left(\dfrac{\sqrt{a}\left(\sqrt{a}+1\right)}{\sqrt{a}+1}+\dfrac{a-4\sqrt{a}+4}{\sqrt{a}-2}\right)\)\(.\dfrac{3}{\sqrt{a}-1}\)
A=\(\left(\dfrac{a-2\sqrt{a}+a-4\sqrt{a}+4}{\sqrt{a}-2}\right).\dfrac{3}{\sqrt{a}-1}\)
A=\(\dfrac{2a-6\sqrt{a}+4}{\sqrt{a}+1}.\dfrac{3}{\sqrt{a}-1}\)
A= \(\dfrac{\left(\sqrt{a}-2\right)\left(\sqrt{a}-1\right)}{\sqrt{a}+1}.\dfrac{3}{\sqrt{a}-1}\)
A= \(\dfrac{3\sqrt{a}-6}{\sqrt{a}+1}\)
P/s: Lần sau đăng thì tách thành từng câu hỏi nhỏ nhé =))
