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Direct and Inverse Variations. Direct Variation. Which of these tables models direct variation? If so, write an equation. NO. Tell if the following graph is a Direct Variation or not. Yes (straight line through the origin!). No. No. No.
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Which of these tables models direct variation? If so, write an equation. NO
Tell if the following graph is a Direct Variation or not. Yes (straight line through the origin!) No No No
example:If y varies directly as x and y = 10 as x = 2.4, find x when y =15. 10x = 36 x=3.6
If y varies directly with x and y = 12 when x = 2, find y when x = 8. Cross multiply: 96 = 2y Solve for y. 48 = y.
The Weight (V) of an object on Venus varies directly as its weight (E) on Earth. A person weighing 120 lb on Earth would weigh 106 lb on Venus. How much would a person weighing 150 lb on Earth weigh on Venus? 150(106) = 120y 15900 = 120y 132.5 pounds =y
Inverse is very similar to direct, but in an inverse relationship as one value goes up, the other goes down. The values of x and y always multiply to give the same value. Inverse Variation
Which of these tables models indirect variation? If so, write an equation. NO
With Direct variation we Divide our x’s and y’s. In Inverse variation we will Multiply them. x1y1 = x2y2 Inverse Variation
If y varies inversely with x and y = 12 when x = 2, find y when x = 8. x1y1 = x2y2 2(12) = 8y 24 = 8y y = 3 Inverse Variation
If y varies inversely as x and x = 18 when y = 6, find y when x = 8. 18(6) = 8y 108 = 8y y = 13.5 Inverse Variation
In kick boxing, it is found that the force, f, needed to break a board, varies inversely with the length, l, of the board. If it takes 5 lbs of pressure to break a board 2 feet long, how many pounds of pressure will it take to break a board that is 6 feet long? 10=6x 1.67 lbs=x