1. Find the dimensions of the rectangle of maximum area that can be formed from a 70-in. piece of wire.
2. Find two positive real numbers such that the sum of the first number squared and the second number is 48 and their product is a maximum.
3. A poster of area 24,000 cm2 has blank margins of width 10 cm on the top and bottom and 6 cm on the sides. Find the dimensions that maximize the printed area.