Question

19. Using an algebraic formula, find the value of 8 - 9a +27a²-27a³, when a = 2
20. Simplify :( use formula): (x + - 2) - (x - 1-2) - (x + -2)(x-1-2)​

Answer 1

19 . use (a-b)^3 = a^3 - b^3 -3a^2b + 3ab^2

20 write que properly plz