\[\boxed{\text{1010.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ (3n - 1)(n + 1) +\]
\[+ (2n - 1)(n - 1) -\]
\[- (3n + 5)(n - 2) =\]
\[= 3n^{2} + 3n - n - 1 + 2n^{2} -\]
\[- 2n - n + 1 - 3n^{2} + 6n -\]
\[- 5n + 10 =\]
\[= 2n^{2} + 10\]
\[если\ n = - 3,5:\]
\[2 \cdot ( - 3,5)^{2} + 10 = 24,5 +\]
\[+ 10 = 34,5\]
\[\textbf{б)}\ (5y - 1)(2 - y) -\]
\[- (3y + 4)(1 - y) +\]
\[+ (2y + 6)(y - 3) =\]
\[= 10y - 5y^{2} - 2 + y - 3y +\]
\[+ 3y^{2} - 4 + 4y + 2y^{2} - 6y +\]
\[+ 6y - 18 =\]
\[= 12y - 24\]
\[если\ \ y = 4:\]
\[12 \cdot 4 - 24 = 48 - 24 = 24.\]