Упростите выражение:
а) $(0,8x + 15)(0,8x - 15) + 0,36x^2$;
б) $5b^2 + (3 - 2b)(3 + 2b)$;
в) $2x^2 - (x + 1)(x - 1)$;
г) $(3a - 1)(3a + 1) - 17a^2$;
д) $100x^2 - (5x - 4)(4 + 5x)$;
е) $22c^2 + (-3c - 7)(3c - 7)$.
$(0,8x + 15)(0,8x - 15) + 0,36x^2 = 0,64x^2 - 225 + 0,36x^2 = x^2 - 225$
$5b^2 + (3 - 2b)(3 + 2b) = 5b^2 + 9 - 4b^2 = b^2 + 9$
$2x^2 - (x + 1)(x - 1) = 2x^2 - (x^2 - 1) = 2x^2 - x^2 + 1 = x^2 + 1$
$(3a - 1)(3a + 1) - 17a^2 = 9a^2 - 1 - 17a^2 = -8a^2 - 1$
$100x^2 - (5x - 4)(4 + 5x) = 100x^2 - (25x^2 - 16) = 100x^2 - 25x^2 + 16 = 75x^2 + 16$
$22c^2 + (-3c - 7)(3c - 7) = 22c^2 - (3c + 7)(3c - 7) = 22c^2 - (9c^2 - 49) = 22c^2 - 9c^2 + 49 = 13c^2 + 49$
Пожауйста, оцените решение