Как решить? -5а(2-а)+(a+5)" 5b"-5с"

- 5a(2 - a) + (a + 5)^2 = 5a(a - 2) + a^2 + 10a + 25 =  = 5a^2 - 10a + a^2 + 10a + 25 =  = 6a^2 + 25 5b^2 - 5c^2 = 5(b^2  - c^2) = 5(b - c) (b + c)