Question

calc optimization prob. field with given area, one side borders a river which costs more to fence. what dimensions will give lowest cost, and what is the cost

Answer 1

I'm doing these right now too. You have to make a system of equations with one being the area equation and the other being the perimeter. Then isolate one of your variables in the area equation and substitute it into the perimeter equation. Find the derivative of the perimeter and solve for your variable. Plug in your new found variable back into the area equation to find the other variable. Plug both variables into the perimeter equation.

Answer 2

Does this make sense?

Answer 3

yes, but what would my eqn for the perimeter be since one side of the fence costs twice as much?

Answer 4

per foot of fenceing

Answer 5

do you have the actual price or just know it's doubled?

Answer 6

the cost for fence along the river is 20$per foot, the other three sides cost10$per foot

Answer 7

and it's a square? since you have three sides at $10 you can make that 30x and the river side 20y to make an equation of 30x+20y=Perimeter.

Answer 8

nope, its a rectangle. not sure if itd be the same. hmm

Answer 9

So then it would be 20x for two of the sides and 10y for one side and 20 y for another, making an equation of 20x+10y+20y=Perimeter. Does that make sense?

Answer 10

Just so you know, I'm not 100% sure on this part

Answer 11

yaaa, that does make sense. i'll try it out, thanks

Answer 12

ok, let me know if it works

Answer 13

oh my, i may have got it. thank you!