=

16

If a+b+ c =9, then ab+bc+ca=23, then a³+b³ + c³ – 3abc =

17

(a-b)³+(b-c)³+ (c-a)³=

19

The product (a+b) (a-b) (a²-ab+b²) (a²+ab+b²) is equal to

20

If = -1, then a³-b³ =