If a sequence is defined recursively by f (0) = 3 and f (n+1) = - f (n) + 5 for n is equal to or greater than 0, then f (2) is equal to?

If f (n+1) = - f (n) + 5

then f (2) = - f (1) + 5

we don't know f (1) yet. Use the same rule as above:

f (1) = - f (0) + 5, we do know that f (0) = 3, so f (1) = - 3+5=2

so f (2) = - f (1) + 5=-2+5=3