Lbs : 4, 8, 12, 16
cost : 6, 12, ?, 24
12 lbs would cost u $ 18 because the apples cost (6/4) = 1.50 per lb
I'm taking the liberty of editing your function as follows: <span>w=4r^2+6s^2, where I use " ^ " to indicate exponentiation.
The partial of w with respect to r is 8r. That with respect to s is 12s.</span>
Answer:
an = (1 + 2·(n - 1))/2^(n - 1) = 2^(1 - n)·(2·n - 1)
sn = 6 - 2·0.5^n·(2·n + 3)