I'm dong a question that involves a sink. The aim is to determine the dimensions of the sink (width and length) which will provide the greated cross-sectional area by modelling using an equation. Here's the catch: you are only allowed a sheet of stainless steel that it 60cm wide and a 5cm overlap has to be allowed for on either side of the sink. So far i've figured this: when: c=cross-sectional ares a=area l=length w=width a= l x w c=a so c= l x w w=60-(10+2L) therefore: c= L[60-(10+2L)] c=60L-10L+2L^2 etc etc. when applying this formula like this: L = c/w L = L[60(10+2L)] / 60(10+2L) eventually L turns out to be 0 (duh i didnt give it a value) But here comes my question: is there a flaw in my formula or am i completely off-track? please help!!!