Question

without actually calculating the cubes , find the value of 50^3-30^3-20^3

Answer 1

a+b+c=0 so,we put 3xyz where x= 50, y= -30 and z=-20 then answer =30000

Answer 2

50^3 - 30^3 - 20^3
=(30+20)^3 - 30^3 - 20^3                ((a+b)^3 -a^3 - b^3)
=3x30x20(30+20)                             (=3ab(a+b))
=90000(Ans)