CALCULUS
posted by JENNY on .
gardner wishes to encloe a rectangular 3000 square feet area with bushes on three sides and a fence on the 4th side .If the bushes cost $25.00per foot and the fence costs $10.00 per foot, find the dimensions that minimize the total cost and find the minimum cost

let the length be x feet, and the width be y feet
we know xy = 3000
so y = 3000/x
You don't say if the fence is along the length or along the width.
I will work it as if it the length has the fence.
If otherwise, just go through it again by changing the equation.
Cost = 10x + 10y + 25(2y)
= 10x + 60y
= 10x + 60(3000/x)
d(cost)/dx = 10 180000/x^2 = 0 for a minimum Cost
10 = 180000/x^2
x^2 = 18000
x = 134.16
y = 3000/x = 22.36
minimum cost = 10(134.16) + 60(22.36) = 2683.28 
thank u sooo much