V (Volume) = s^2 * h = 48 ------> h = 48s^-2
C (Cost) = (4sh)(2) + (2s^2)(1) = 2s^2 + 8sh = 2s^2 + 8s(48s^-2) = 2s^2 + 384s^-1
dC/ds = 4s - 384s^-2 = 0 ------> 4s(1 - 96s^-3) = 0
Since s can't be 0, the only possible solution is:
1 - 96s^-3 = 0
s^3 - 96 = 0
s = cube root(96) = 2 cube root(12) ~ 4.579 cm
s^2 = 4 + 2 cube root(18) = 2[2 + cube root(18)]
h = 48/s^2 = 24/[2 + cube root(18)] ~ 5.194 cm
C) 7 pounds 10 ounces 7 5/8
3 ponds + 4 pounds = 7 pounds
8 ounces + 2 ounces = 10 ounces
16 ounces in a pound
7 pounds 10/16 ounces
reduce '10/16' to '5/8'
Jamil has already 6 3/4 cups of butter.
He need 12. SO in order to get the needed butter, we subtract 6 3/4 to 12.
= 12 - 6 3/4
= 11 4/4 - 6 3/4
= 5 1/4
So Jamil needs 5 1/4 cups of butter to achieve the 12 cups.
