please answer question a & b

Multiple-Output Cost Function in Action - Suppose a firm produces two goods and has cost function given by C=1000.5Q1Q2+(Q1)2+(Q2)2 - If the firm plans to produce 4 units of Q1 and 6 units of Q2 - Does this cost function exhibit cost complementarities? - Yes, cost complementarities exist since a=0.50 a) Is there any economies of Scale? Prove your stance mathematically. b). Is there any cost complementarity? Prove mathematically