USAMO 2018 (Problem 1)
Let be positive real numbers such that . Prove that .
WLOG, assume .
We should prove .
Use 24. Square of a Sum.
Add to both sides.
We should prove .
Use .
We should prove .
Use 28. AM–GM Inequality.
By using 28. AM–GM Inequality, .
Multiply both sides of Hint 9 by 8 to get the desired result.