Find the maximum profit and the number of units that must be produced and sold in order to yield the maximum profit. Assume that​ revenue, Upper R (x )​, and​ cost, Upper C (x )​, are in thousands of​ dollars, and x is in thousands of units. Upper R (x )equals9 x minus 2 x squared​, Upper C (x )equalsx cubed minus 3 x squared plus 4 x plus 1