Question

-7a - (3a - 5c), якщо c - 2a = -5

Answer 1

Ответ:

-7a - (3a - 5c)=(-7-3a)-5c=10a - 5c

Answer 2

Ответ:

5a - 3c)(5a + 3c) - (7c - a)(7c + a) = (5a)^2 - (3c)^2 - ((7c)^2 - a^2) = 25a^2 - 9c^2 - (49c^2 - a^2) = 25a^2 - 9c^2 - 49c^2 + a^2 = 25a^2 + a^2 - 9c^2 - 49c^2 = 26a^2 - 58c^2.

Ответ:  26a^2 - 58c^2.