## nature of cost curves

Q1. Given the following total cost functions, investigate the nature of average and marginal cost curves.
i) C=0.0003Q^2+6.75Q-10485
ii) C=0.8Q+3000

In case of (i), AC= 0.0003Q+6.75-10485/Q. Here d(AC)/dQ>0 and d^2(AC)/dQ^2 <0. So this AC curve is rising upwards and is convex upwards.
Again MC=0.0006Q+6.75. Here d(MC)/dQ>0 and d^2(MC)/dQ^2 =0. So this MC curve is rising upwards and is a straight line.

Is it correct to write the answer like this? What am I supposed to write in case of (ii)?