<PRE><B>Question 597839</B>
Using calculus is one way to solve the problem, and is probably the most common way. It is also possible to solve this one without calculus.


If you know the AM-GM (arithmetic mean-geometric mean) inequality, you can say that


*[tex \LARGE \frac{2w + \frac{70}{w}}{2} \ge \sqrt{2w(\frac{70}{w})}]


*[tex \LARGE \frac{2w + \frac{70}{w}}{2} \ge \sqrt{140}]


By AM-GM, equality occurs if and only if *[tex \LARGE 2w = \frac{70}{w} \Rightarrow w = \sqrt{35}].</PRE>