Answer:
-1280
Step-by-step explanation:
There are 2 ways you could do this. You could just do the question until you come to the end of f(4). That is likely the simplest way to do it.
f(1) = 160
f(2) = - 2 * f(1)
f(2) = -2*160
f(2) = -320
f(3) = -2 * f(2)
f(3) = -2 * - 320
f(3) = 640
f(4) = - 2 * f(3)
f(4) = - 2 * 640
f(4) = - 1280
I don't know that you could do this explicitly with any real confidence.
