help me again...?

Question

still suck in this problem
consider a rectangular box with a square base and surface area of 216 square inches. let x represent the length of each side base and h represent the height of the box
c. if the surface area is 216square inch ..express the variable h in term of x?
d. find the volume of box in term of x alone ?
(-_-) .. i kinda forgot all the Formulas ... plz help me again .. thank so much

Answer 1

Surface area is the sum of the areas of all six sides. You have two sides (specifically, the top and bottom) which are x-by-x, and four sides which are x-by-h. Thus surface area = 2x²+4xh=216. Thus for part c:
2x²+4xh=216
4xh=216-2x²
h=54/x-x/2

For part d, remember that volume equals length times width times height, thus V=x*x*h. Substituting the value obtained in the previous step for h, we get:

V=x²(54/x-x/2)
V=54x-x³/2

Answer 2

A = 216 IN^2 = 2(x*x+x*h+x*h) = 2x(x+2h)
2x^2+4xh = 216
h = 216/(2x^2+4x)

Answer 3

surface area of cuboid is= 2(lb+bh+lh)
216= 2(x^2+ hx+ hx)
108= x^2 + 2hx
h= (108- x^2)/2x

volume= lbh
= x*x*h
= x^2 *(108- x^2)/2x
= x/2(108- x^2)

Answer 4

http://www.math.com/tables/geometry/