need help understanding

Exercise 1 - Critical points. (3pts total) Find and classify (in terms of max/min/saddle/inconclusive text) all critical points for the functions: (a) f(z,y) =br?y 2xy +30zy 3, z e R,y eR (Ipt) (b) f(z,y) = sin(y)sin(z), =,y [0,2x] (1pt) Hint: Remember that critical points occur, by definition, only on the domain's interior (i.e., on open domains). () flz,y) =ysin(z), xeR,yeR (Ipt) Exercise 2 - Maximizing profit selling watches. (4pts total) A company has developed a profit model that depends on x, the number of watches sold per month and the number of hours spent advertising y per month, according to z = f(z,y) = 48z 4 96y 2 3y 9y, where z is measured in thousands of dollars. The maximum number of watches that can be sold a month is 50 and the maximum amount of hours spent advertising is 25. For the purpose of this question, please treat x and y as positive real numbers! Find the values z and y that maximize the profit, and find the maximum profit. (Hint: Remember, extrema occur inside the function domain, or at the boundary of the domain)