Binomial Theorem Question (1 Viewer)

[Doom of Valariya]

Can someone please help me with this question for binomial theorem:

In the expansion of (1+3x+ax²)ⁿ, where n is a positive integer, the coefficient of x² is 0. Find in terms of n, the value of:
(a) a
(b) the coefficient of x

Thanks

 

[amberbambi]

Where does 'a' come into play?

 

[Doom of Valariya]

Terribly sorry it is meant to be (1+3x+ax^2)^n

 

[integral95]

Hint, make your brackets like

then expand the terms normally with the binomial stuff