Question

The variable z varies jointly with x and y. If z = 18 when x = 2 and y = 6, find the constant of variation, k, and then find the value of z when x = −4 and y = 5.

The constant of variation k is _____.
The value of z is _____.

Answer 1

The constant of variation k is 3/2.

The value of z is -30.

Explanation:

As we know Function form is

Z=kxy-------------1

So for k

K = z/xy

So if z=18, x=2 y=6

k= 18/2 x6

k= 18/12

k=3/2

Now we have to find for z, now we know the value of x= -4 y =5 z =3/2

z= kxy

z= 3/2 (-4)(5)

z= -30