(1)(a+1/a)²已知 --> a²+1/a² = known. But we can't tell which one is bigger, a² or 1/a²? (2))(a-1/a)²已知 --> a²+1/a² = known. But we can't tell which one is bigger, a² or 1/a²?
Combining 1) and 2) is the same. a²+1/a² = known. But we can't tell which one is bigger, a² or 1/a²?