please do it asap

i am stuck in this

Section 4.3: 130, 140. 130. [6 marks] Find the local and absolute minima and maxima for the function y = x3 12x over the interval (-00,00). 140. [3 marks] A company that produces cell phones has a cost function of C(x) = x2 1200x + 36, 400, where C is the cost in dollars and x is the number of cell phones produced (in thousands). How many units of cell phones (in thousands) minimizes this cost function