Optimization Promblems? - Printable Version +- Twitist Forums (http://twitist.com) +-- Forum: General Social Media & Marketing Forums (/forum-8.html) +--- Forum: SEO Search Engine Optimization (/forum-30.html) +--- Thread: Optimization Promblems? (/thread-138647.html) |
Optimization Promblems? - luca - 04-10-2014 03:33 PM A fence is to be built to enclose a rectangular area of 290 square feet. The fence along three sides is to be made of material that costs 3 dollars per foot, and the material for the fourth side costs 14 dollars per foot. Find the dimensions of the enclosure that is most economical to construct. - girish - 04-10-2014 03:39 PM Sides should be 10.12 ft x 28.66 ft Once side of 10.12 ft can be constructed with costly material , and cost will be minimum. Lets say sides of fence be L & B. Area = L * B = 290 Thus L = 290/B Cost = 3L+3L+3B+14B = 6L + 17B = 6*290/B + 17B = 1740*B^-1 + 17B This is cost expressed in therms of B For cost to be min/max derivative of this should be zero. d/dB ( 1740*B^-1 + 17B ) = 0 -1740*B^-2 + 17 = 0 B = sqrt (1740/17) = 10.1169630 L = 290/B = 28.664728 |