Question

if a= 3+b,then find the value of a³-b³-9ab

Answer 1

Hope this will help you....

Answer 2

if a=3+b
Find a^3-b^3-9ab
a^3=(3+b)^3
=27+3×3×b (3+b)+b^3
=27+27b+9b^2+b^3
9ab=9 (3+b)(b)
=27b+9b^2
So, a^3-b^3-9ab=
(27+27b+9b^2+b^3)-(b^3)-(27b+9b^2)
=27+27b+9b^2+b^3-b^3-27b-9b^2
=27
Hope u understand