TeX джерело:

\begin{array}{l}(2{x^2} - 3x + 2) - (3{x^2} - 2x - 1) - {x^2} + 2x + 1 + ( - 2{x^2} + x - 1) = \\ = 2{x^2} - 3x + 2 - 3{x^2} + 2x + 1 + {x^2} - 2x - 1 - 2{x^2} + x - 1 = - 2{x^2} - 2x + 1\end{array}