Joint variation

The equation for a Joint Variation is represented as:

• y = kx

• y = k/x

• y = kxz

• y = kx/z

Solve for the constant of variation, k. (Use / for the fraction bar)

y varies jointly as x and z. x= -2, when y=3 and z= -4

(a)  

If y varies jointly with the product of x and z, and y = 105 when x = 5 and z = 7, find y when x = 9 and z = 10.

• 270

• 180

• 360

• 255

If y varies jointly with the product of x and z, and y = 1000 when x = 10 and z = 20, find y when x = 8 and z = 10.

• 100

• 200

• 300

• 400

The variable x is in joint variation with y and z. When the values of y and z are 4 and 6, x is 16. What is the value of x when y = 8 and z =12?

• 32

• 64

• 48

• 96

z varies jointly with x and y. If x = 2, y = 3 and z = 4, find z when x = -6 and y = 2.

• -6

• -8

• -10

• -12

z varies jointly with x and y. If x = 5, y = -1, and z = 10. Find z when x = -1/2 and y = 7.

• 5

• 6

• 7

• 8

z varies jointly with x and y. If x = 7, y = 3 and z = -14, find y when z = -8 and x = 3.

• 3

• 4

• 5

• 6

z varies jointly with x and y. If x = 8, y = -3 and z = -6, find x when z = 12 and y = -16.

• -3

• -4

• -6

• -9

y varies jointly as x and z.

If y= -40 when x= -2 and z= -1, find y when x=4 and z= -3.

(a)