# Mathematical proof

## Homework Statement

Let a,b be in the positive reals. Prove a/b+b/a is >=2

## The Attempt at a Solution

I have no idea. Maybe add the two ratios: (a^2+b^2)/a*b and then try to analyze separately the numerator and denominator?

jbriggs444
Homework Helper
Those a's and b's in the denominator are pesky. Why not multiply through by ab and see what that gives you?

Those a's and b's in the denominator are pesky. Why not multiply through by ab and see what that gives you?
I feel like this is related to the law of cosines

jbriggs444