# In the binomial expansion of #(1+ax)^n#, where #a# and #n# are constants, the coefficient of #x# is 15. The coefficient of #x^2# and of #x^3# are equal. What is the value of #a# and of #n#?

##### 1 Answer

Nov 26, 2017

#### Explanation:

The formula for the binomial expansion of

Therefore the

If the

Taking out factors of

which expands to:

We know that

You can check the answer by putting it back into the original formula.