Direct Variation

If y varies directly with x, and y = -20 when x = 3, what is y when x = 15?

• 100

• -2.25

• 2.25

• -100

If y varies directly with x, and y = 8 when x = 3, what is x when y = -56?

• 21

• -21

• -149.33

• 149.33

If y varies directly with x, and y = 21 when x = -7, what is y when x = 42?

• -126

• 14

• -14

• 126

Tags

CCSS.7.RP.A.2B

If y varies directly with x, and y = 16 when x = 32, what is y when x = -60?

• -30

• -120

• 30

• 120

If y varies directly with x, and y = 22 when x = -11, what is y when x = 24?

• -48

• -12

• 48

• 12

Determine if the relationship between the two quantities is a direct variation. Explain your reasoning.

• yes, the constant of variation is 1/2

• yes, the constant of variation is 2

• no, there is constant of variation.

Tags

CCSS.8.EE.B.5

CCSS.8.F.A.3

CCSS.8.F.B.4

CCSS.8.F.B.5

CCSS.8.SP.A.2

Determine if the relationship between the two quantities is a direct variation. Explain your reasoning.

• no, there is no constant of variation

• yes, the constant of variation is 100

• yes the constant of variation is 50

Tags

CCSS.8.EE.B.5

CCSS.8.EE.B.6

CCSS.8.F.A.3

CCSS.8.F.B.4

Determine if the relationship between the two quantities is a direct variation. Explain your reasoning.

• yes, the constant of variation is 8.

• no, there is no constant of variation

• yes, the constant of variation is 1/8

Tags

CCSS.8.EE.B.5

CCSS.8.EE.B.6

CCSS.8.F.A.3

CCSS.8.F.B.4

CCSS.8.SP.A.3

Determine if there is a constant of variation. If so, explain what it represents.

The equation y = 9.50 x represents the number of dollars y Marty paid for x movie tickets.

• The constant of variation is 9.50. This means that Marty paid $9.50 for each movie ticket

• There is no constant of variation. There is not a direct variation between the number of tickets and the total cost.

Tags

CCSS.8.EE.B.5

CCSS.8.EE.B.6

CCSS.8.F.B.4

CCSS.8.SP.A.3

Determine if there is a constant of variation. If so, explain what it represents.

The equation y = 0.10 x + 45 represents the cost y of a cell phone plan when x text messages are sent and received.

• The constant of variation is $0.10. + 45. This means that for every text message sent, you pay 0.10 + $45.

• There is no constant of variation. The cost does not vary directly with the number text messages sent and received.

Tags

CCSS.HSF.LE.B.5