For all positive integers x, f(x)=f(x+1). If f(3)=15, then what is f(7)?
Choose the correct choice from the following choices: A) 8 B) 12 C) 15 D) 21 E) 35
Here we go---   f(x) = f(x+1) ---(1)   f(3) = 15 ----(2)   Now   f(7) = f(6+1)-----&gt; f(6) = f(5+1)-------&gt; f(5) = f(4+1) ------&gt; f(4) = F(3+1)---&gt; f(3) = 15   Now backtrack   f(4) = 15-----&gt; f(5) = 15 ------&gt; f(6) = 15 ----&gt; f(7) = 15   Though I picked option 15   I am still not 100% sure of the answer(don't know why)   My bets on 15.
<result>C</result>
For all positive integers x, f(x)=f(x+1). If f(3)=15, then what is f(7)?