I was looking through my Calculus book from long time ago, and I came across a problem that I could not solve. It said, not to substitute numbers to solve the problem. It wants us to show proofs like geometry. The problem is: Prove that- Square root of AB is less than or equal to 1/2(a+b). Sorry I do not have the square root button, but the AB is inside the square root sign. And 1/2- is One-half as in fraction. I also do not have to Less than or equal to sign to type. thanks for all your help.