Solve the Problem $M(x, y)=20 x^{2}+40 y^{2}-3 x y$ , Where $x$

Multiple Choice

Solve the problem.
-Suppose that the manufacturing cost of a precision instrument is approximated by $M(x, y) =20 x^{2}+40 y^{2}-3 x y$ , where $x$ is the cost of materials and $y$ is the cost of labor. Find $\mathrm{M}_{\mathrm{X}}(4,9)$ .

A) 708
B) 212
C) 3132
D) 133