Question

A sequence is defined recursively by f(1)=16 and f(n)=f(n-1)+2n. Find f(4)

1) 32

2) 30

3) 28

4) 34

Answer 1

`f(1)=16 \ \ \ and \ \ \ \ f(n)=f(n-1)+2n \\ \\f(2)=f(1)+2\cdot2=16+4=20\\ \\f(3)=f(2)+2\cdot3=20+6=26\\ \\f(4)=f(3)+2\cdot4 =26+8=34`


`Ans.\ 4)`