A supply company manufactures copy machines. The unit cost C (the cost in dollars to make each copy machine) depends on the number of machines made. If x machines are made, then the unit cost is given by the function C(x) = 0.2x2 – 36x+20,266. What is the minimum unit cost? Do not round your answer.​

To answer the problem above, it is best to use the elimination method. We can add up the linear equations to eliminate y. This is shown below,
 
                                               2x + y = 1
                                           +  3x - y = -6

This results to, 
                                               5x = -5

which when simplified gives x = -1. 
Substituting this value of x to any of the equation,

                                               2(-1) + y = 1

                                                     y = 3

Thus, the solution to these linear equations is (-1, 3).