Question

разложите на множители.

Answer 1

1) b³-8c³=(b-2c)(b²+2bc+4c²)
2) 49x²y-y³=y(49x²-y²)=y(7x-y)(7x+y)
3) -7a²+14a-7=-7(a²-2a+1)=-7(a-1)²
4) 5ab-15b-5a+15=5(ab-3b-a+3)=5(b(a-3)-(a-3))=
    =5(a-3)(b-1)
5) a⁴-1=(a² -1)(a² +1)=(a-1)(a+1)(a² +1)

Answer 2

Думаю, что так:
b³-8c³= b³-2³c³= (b-2c) ( b²+2bc+4c²)

49x²y- y³ = y(7²x²-y²)=y (7x-y)(7x+y)

-7a²+14a-7 = -7 (a²-2a+1) = -7*(a-1)²

5ab-15b-5a+15=(5ab-15b) + (15-5a)=
=5b (a-3) +5 (3-a)= 5b(a-3)-5(a-3)=
=(a-3)(5b-5)= 5(b-1)(a-3)

a⁴-1 = (a²)²-(1²)²= (a²-1)(a²+1) = (a-1)(a+1)(a²+1)