Разложите на множители:

6 а^2-6

5 а^2+10 аб+5 б^2

х+5 у+х^2-25 у^2

9-с^2+а^2-6 а

1) 6a2-6=6a (a-1) (a+1)

2) 5a2+10ab+5b2=5 (a+b) ^2

3) x+5y+x2-25y2=x (1+x) + 5y (1-5y) (1+5y) = (x+5y) (1+x) (1-5y) (1+5y)

4) 9-c2+a2-6a = (3-c) (3+c) + a (a-6) = (3-c) (3+c) (1+a) (a-6)