I have no problems with drawing the graph. I got that function is symmetrical about the x axis, roots at and and a turning point you have a closed loop between 0 to 3a and then y just increases with x increasing.A curve has equation

where a is a positive constant

a) Sketch a graph of the curve and showing stationary points and intersection with the axes

b) show that the arc length of C in the first quadrant form the point up to is given by

My only problem is the arc length part. I could do with a pointer.

Thanks Bobak