The curve y= 2x/(1+x^2) has

1. exactly three points of inflection seperated by a point of maximum and a minimum.

2. exactly two points of inflection with a point of maximum lying between them.

3. exactly two points of inflection with a point of minimum lying between them.

4. exactly three points of inflection seperated by two points of maximum.

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My working: I derived the above expression and found the derivative to be 0 at x=1,-1 . So i really dont know how can there be three points of inflection at all.