Question

What is the fourth term of the expansion of the binomial (2x + 5)5

Answer 1

In the expansion of \[\left( x+a \right)^n\]
(r+1)th term is
\[T _{r+1}=C _{r}^{n}x ^{n-r}a ^{r}\]
put x=2x,a=5
n=5
and calculate.

Answer 2

r+1=4
r=4-1=3