Question

If f(x+1)-f(x)=2 and f(1)=5 what is f(6)

Answer 1

Find x using f(1)=5
using x find f(6)

Answer 2

\[f(x+1)-f(x) = 2\]
\[f(1+1)-f(1)=2\]\[f(2)-5=2 \ \ \rightarrow f(2)=7\]
Continue plugging in and you'll find this pattern:
5, 7, 9, 11, 13, 15, ...