a - ( (b) / (c+x^2) )

The line goes through (2, ) and the gradient of the curve is at its maximum at x= root6/3 (square root of 6 divided by 3)

Prove a = 1, b = 2, c = 2.

Can I please have a detailed solution to this? I've tried so many ways, been hours already. It was in the dydx and integration section.