Question

Suppose y varies jointly as x and z. Find y when x=9 and z=-3, if y=-50 when z is 5 and x is -10.

Answer 1

y = -27 when x = 9 and z = -3

Explanation:

y = kxz is the joint variation where k is a constant

Substitute the knowns in to find k

-50 = k( -10)(5)

-50 = -50k

k = 1

y = xz

Now find y

y = 9*-3

y = -27 when x = 9 and z = -3