assume that the marginal product of each input employed by Microsoft depends only on the quantity of that input employed (and not on the quantities of other inputs), and that the diminishing marginal returns hold for each input. Explain why Microsoft isoquants must be convex if these assumptions hold.
Do a little research, and then take a shot. What do you think?
Hint: You can answer this logically. Remember what an Isoquant represents. Start at a production point with inputs X0 and Y0. If X changed, how much would Y need to change to remain on the same Isoquant? If X changed again, how much would Y need to change to remain on the same isoquant.