Giải HPT:
\(\left\{{}\begin{matrix}3x-6y=1959\\x+7y=2019\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3x-6y=1959\\3x+21y=6057\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}27y=4098\\x+7y=2019\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y\approx152\\x=955\end{matrix}\right.\)
Mik chỉ làm gần bằng đc thôi vì y là số thập phân.
1) \(A=\dfrac{\sqrt{2+\sqrt{3}}}{\sqrt{2}}=\dfrac{\sqrt{4+2\sqrt{3}}}{2}=\dfrac{\sqrt{\left(\sqrt{3}+1\right)^2}}{2}=\dfrac{\sqrt{3}+1}{2}\)
2) \(\left\{{}\begin{matrix}3x-6y=1959\\x+7y=2019\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}3x-6y=1959\\3x+21y=6057\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x+7y=2019\\27x=4098\end{matrix}\right.\)\(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{8609}{9}\\y=\dfrac{1366}{9}\end{matrix}\right.\)
