The function is k(x) = 512 · x .
Try 'A': k(2/3) = (512) · (2/3) = 341.33... not 64
Try 'B': k(4/9) = (512) · (4/9) = 257.55... not 16
Try 'C': k(1/3) = (512) · (1/3) = 170.66... not 8
Try 'D': k(2/9) = (512) (2/9) = 113.77... not 8 .
So far, it looks like NONE of the choices is correct.
But wait ! There's more !
What if the actual function is k(x) = 512ˣ
that is, 512 raised to the 'x' power ?
That would be a horse of a different cruller.
Let's try THAT out.
First, here are two facts that we'll need:
==> 512 ^ 1/3 = 8
and
==> 512 ^ 1/9 = 2 .
OK. NOW ...
Try 'A': k(2/3) = (512) ^ 2/3 = 8^2 = 64 yes !
Try 'B': k(4/9) = (512) ^ 4/9 = 2^4 = 16 yes !
Try 'C': k(1/3) = (512) ^ 1/3 = 8 yes !
Try 'D': k(2/9) = (512) ^ 2/9 = 2^2 = 4 not 8 .
So here's what we have learned:
-- The function in the question is actually k(x) = 512 ^ x
-- Choice-D is the incorrect one.
