sir plz solve it

M = tan + 2xy (a) If X - y , then determine the value of axcy (Choose II-Deduction from Euler's Theorem) (b) Find all local maxima, local minima, and saddle points of the given function. /(x,y)= x' - y' - 2x+4y+6 (c) Show that w= sin(x + cr) + cos(2x+2cr). Satisfies one-dimensional wave equation