17.
\(10-6x+12y+9x^2+4y^2=0\)
\(\Leftrightarrow\left(\left(3x\right)^2-2.3x.1+1\right)+\left(\left(2y\right)^2+2.2y.3+3^2\right)=0\)
\(\Leftrightarrow\left(3x-1\right)^2+\left(2y+3\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(3x-1\right)^2=0\\\left(2y+3\right)^2=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{1}{3}\\y=-\dfrac{3}{2}\end{matrix}\right.\)
19.
\(x^2+9y^2+6y+5+4x=0\)
\(\Leftrightarrow\left(x^2+2.x.2+2^2\right)+\left[\left(3y\right)^2+2.3y.1+1^2\right]=0\)
\(\Leftrightarrow\left(x+2\right)^2+\left(3y+1\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(x+2\right)^2=0\\\left(3y+1\right)^2=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-2\\y=-\dfrac{1}{3}\end{matrix}\right.\)
Mấy bài tiếp theo làm tương tự nhé. :)) Chứ dài quá làm không nổi.
