Question

Value of 21 cube - 20 cube

Answer 1

21^3=9261,20^3=8000

9261-8000=261

Answer 2

Answer:

21^3-20^3

=(21-20){(21)^2+(20)^2+(21*20)

=1(441+400+420)

=1(1261)

=1261

using a^3-b^3=(a-b)(a^2+b^2+a*b)