Respuesta :

Answer:

z = 5xy

Step-by-step explanation:

since z varies jointly with x and y then

z = kxy ← k is the constant of variation

to find k use the given condition z = - 75 when x = 3 and y = - 5

k = [tex]\frac{z}{xy}[/tex] = [tex]\frac{-75}{-15}[/tex] = 5 and

z = 5xy ← equation of variation

Answer: z=kxy, k=5, z=-10

Step-by-step explanation: hope that helps