To Find : term independent of x, i.e. x⁰

For

a=3x, and n=15

We have a formula,

Now, to get coefficient of term independent of xthat is coefficient of x⁰ we must have,

(x)^15-3r = x⁰

• 15 - 3r = 0

• 3r = 15

• r = 5

Therefore, coefficient of x⁰

Conclusion : coefficient of x⁰