For questions 1-3

Determine whether the equation represents a direct variation. If it does, find the constant of variation.

1. 2 y = 5x +1
   

ANot a direct variation

BDirect variation, constant of variation is 5/2

CDirect variation, constant of variation is 2/5

DDirect variation, constant of variation is 1 -2/5

1. -12x = 6y
   

ANot a direct variation

BDirect variation, constant of variation is 1/2

CDirect variation, constant of variation is 2

DDirect variation, constant of variation is -2

1. .7x -1.4y = 0
   

ANot a direct variation

BDirect variation, constant variation is 1/2

CDirect variation, constant variation is 2

DDirect variation, constant variation is -2

For questions 4-6

Suppose y varies directly with x. Write a direct variation equation that relates x and y.

1. y= -10 when x =2
   

Ay= -5x

By= -1/5x

Cy= 5x

Dy= 1/5 x

1. y= 7 1/2 when x=3
   

Ay= 3/2x

By= 2/3x

Cy= 5/2

Dy= 2/5

1. y=10.4 when x=4
   

Ay= 3.4x

By= 3.8x

Cy= 3.2x

Dy= 2.6x

For questions 7 and 8

For the data in the table, tell whether y varies directly with x. If it does, write an equation for the direct variation.

1. (x.y)
   

(3, 5.4)

(7, 12.6)

(12, 21.6)

ANot a direct variation

BDirect variation, y= 1.8x

CDirect variation, y= 4x

DDirect variation, y= 5/9x

1. (x,y)
   

(-2,1)

(3,6)

(8,11)

ANot a direction variation

BDirect variation, y=x

CDirect variation, y=2x

DDirect variation, y= -2x