Question

-x²+13y²-5y+7x²-8y²+2y​

Answer 1

$\begin{aligned}&\sf{-x^{2}+13 y^{2}-5 y+7 x^{2}-8 y^{2}+2 y^{2}}\\&\textbf { Group like terms }\\&\sf{=13 y^{2}-8 y^{2}+2 y^{2}-5 y-x^{2}+7 x^{2}}\\&\textbf { Add similar elements: }-\mathrm{x}^{2}+7 \mathrm{x}^{2}=6 \mathrm{x}^{2}\\&\sf{=13 y^{2}-8 y^{2}+2 y^{2}-5 y+6 x^{2}}\\&\textbf { Add similar elements }: 13 \mathrm{y}^{2}-8 \mathrm{y}^{2}+2 \mathrm{y}^{2}=7 \mathrm{y}^{2}\\\end{aligned}$

$\sf{=7 y^{2}-5 y+6 x^{2}}$