Can someone please help me solve this?

-15

Step-by-step explanation:

df(x, y) / dy = lim (f(x, y+h) - f(x, y)) / h =

lim (e^x^2 - 15y - 15h - e^x^2 ‐ 15y) / h = lim -15h / h = -15

so, the first derivative of f(x,y) by y is simply a constant : -15

fy (x, y) = -15 for any and every values of x and y.

the fast track would be derivative calculation :

the derivative by y makes x a constant. and every constant is eliminated for derivation.

so, e^x^2 goes away (= 0 in the derivative).

that leaves -15y = -15×y¹. its derivative simply is

1×-15×y⁰ = -15