\[\boxed{\text{983.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ (x + 7)^{2} - (x - 5)(x + 19) =\]
\[= x^{2} + 14x + 49 -\]
\[- \left( x^{2} + 19x - 5x - 95 \right) =\]
\[= x^{2} + 14x + 49 - x^{2} - 14x +\]
\[+ 95 = 144\]
\[\textbf{б)}\ (x + 9)^{2} + (8 - x)(x + 26) =\]
\[= x^{2} + 18x + 81 + 8x + 208 -\]
\[- x^{2} - 26x = 289\ \]