\[\boxed{\text{963.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ a - b + a^{2} - b^{2} = (a - b) +\]
\[+ (a - b)(a + b) =\]
\[= (a - b)(1 + a + b)\]
\[\textbf{б)}\ c² + d - d^{2} + c =\]
\[= (c - d)(c + d) + (c + d) =\]
\[= (c + d)(c - d + 1)\]