1) 3(x-4)^2-3x^2 2)25x-x^3 3)2x^2--20x+50 4)(c^2-b)^2-(c^2-1)*(c^2+1)+2bc^2; если b=-3 5)(x-4)^2-25x^2 6)a^2-b^2-4b-4a 7)(a+b)^2-(a-b)^2=4ab

Упростим выражения:

1) 3 * (x - 4)^2 - 3 * x^2 = 3 * (x^2 - 2 * x * 4 + 4^2) - 3 * x^2 = 3 * (x^2 - 8 * x + 16) - 3 * x^2 = 3 * x^2 - 3 * 8 * x + 3 * 16 - 3 * x^2 = -3 * 8 * x + 3 * 16 = -3 * 8 * x + 3 * 8 * 2 = 24 * (2 - x); 

2) 25 * x - x^3 = x * (25 - x^2) = x * (5 - x) * (5 + x); 

3) 2 * x^2 - 20 * x + 50 = 2 * (x^2 - 10 * x + 25) = 2 * (x - 50^2; 

4) (c^2 - b) ^ 2 - (c^2 - 1) * (c^2 + 1) + 2 * b * c^2, если b = -3;  

(c^2 - (-3)) ^ 2 - (c^2 - 1) * (c^2 + 1) + 2 * (-3) * c^2; 

(c^2 + 3) ^ 2 - (c^2 - 1) * (c^2 + 1)  - 6 * c^2;  

c^4 + 6 * c^2 + 9 - c^4 + 1 - 6 * c^2 =  9 + 1 = 10; 

5) (x - 4)^2 - 25 * x^2 = (x - 4)^2 - (5 * x)^2 = (x - 4 - 5 * x) * (x - 4 + 5 * x) = (-4 - 4 * x) * (6 * x - 4) = -4 * (x + 1) * 2 * (3 * x - 2) = -8 * (x + 1) * (3 * x - 2); 

6) a^2 - b^2 - 4 * b - 4 * a = (a - b) * (a + b) - 4 * (a + b) = (a + b) * (a - b - 4); 

7) (a + b)^2 - (a - b)^2 + 4 * a * b = (a + b + a - b) * (a + b - a + b) + 4 * a * b = 2 * a * 2 * b + 4 * a * b = 4 * a * b + 4 * a * b = 8 * a * b.