3)`2x^2+x-10=0`
`2x^2-4x+5x-10=0`
`<=> 2x(x-2)+5(x-2)=0`
`<=>(2x+5)(x-2)=0`
\(=>\left[{}\begin{matrix}2x=-5\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{5}{2}\\x=2\end{matrix}\right.\)
1)\(A=3\sqrt{27}-4\sqrt{75}+2\sqrt{108}=3\sqrt{3^2.3}-4\sqrt{5^2.3}+2\sqrt{6^2.3}\)
\(=9\sqrt{3}-20\sqrt{3}+12\sqrt{3}=\sqrt{3}\)
2)\(\left\{{}\begin{matrix}2x-y=7\\3x+2y=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=2x-7\\3x+4x-14=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=2x-7\\7x=14\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=2.2-7=-3\\x=2\end{matrix}\right.\)
