PROGRAMMING:Quadratic equation of one variable

Input three coefficients to find the solution of quadratic equation with one variable, and output all possible cases, including complex roots.
###Input format:
Three real numbers a, B, C
###Output format:
According to the output sample format output, pay attention to the output order.
###Input example:
```in
1 6 9
```
###Output example:
```out
x1=x2=-3.000000
```
###Input example:
```in
1 -5 6
```
###Output example:
```out
x1=3.000000,x2=2.000000
```
###Input example:
```in
1 1 9
```
###Output example:
```out
x1=-0.500000+2.958040i
x2=-0.500000-2.958040i
```







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