(b-7)^2 - (b-7)(b+7) = (b-7) * (b-7-(b+7)) = (b-7) * (-14) = -14 (b-7)
Подставим b = 2,5
-14 * (-4,5) = 63
(b-7)^2 - (b-7)(b+7) = (b-7) * (b-7-(b+7)) = (b-7) * (-14) = -14 (b-7)
Подставим b = 2,5
-14 * (-4,5) = 63