Two sides of a+ 1/a=4 are multiplied by a to get a2-4a+ 1=0, (a is not equal to 0); Using the root formula: [-b+- root (b 2-4ac)]/(2a), we get a=2, plus or minus 2 roots 3. According to the root number A in the problem 1, a >: 0, so the problem of removing 2-2 roots 3 and getting a=2+2 roots 3, 1 and 2 is solved.