ļ½ Translate the following phrases. 1. fifty less than 2 times x šš − šš š 2. the quotient of 6 and y, increased by one + š š 3. the product of z and five more than z š³(š + š) List the characteristics of Direct proportion/variation. Formula: y=kx y x Graph: Straight line that goes through origin Formula for k: k ļ½ X & Y Relationship: They move in the same direction – up together or down together. List the characteristics of Inverse proportion/variation. k Formula: y ļ½ x Formula for k: k=yx Graph: The line curves & will never touch the x or y axis. X & Y Relationship: They move different directions. 3. When you are given a table of values for x and y, how can you tell if it represents a direct, an inverse proportion (variation) or neither? Look to see if you can find a constant. AND If the variables have a relationship. 4. Looking at the following table of values k=yx X 1 2 3 6 Y 6 3 2 1 6 6 6 6 Do the points represent a direct proportion (variation), inverse proportion (variation), or neither? Inverse 5. What is the constant of variation in the following table? y kļ½ x X 8 6 5 12 Y 64 48 40 96 8 8 8 8 Example of Direct 40 6. What type of proportion (variation) is y ļ½ ? x Inverse What is the constant? 40 7. What type of proportion (variation) is y ļ½ 6 x ? Direct What is the constant? 6 8. If y varies inversely with x, and y=6 and x=7, what is the rule (equation) for this proportion (variation)? k k Multiply both yļ½ 6 ļ½ sides by 7 x 7 k = 42 42 yļ½ x 9. If x varies inversely with y. If x=8 when y=2, what is the value of y when x=4? k Multiply both k 16 2ļ½ yļ½ yļ½ x 8 sides by 8 k = 16 4 y=4 10. If y=15 and x=6, using an inverse proportion (variation), what is the value of y when x=18? Multiply k k yļ½ 15 ļ½ both sides x 6 by 6 k = 90 90 yļ½ 18 y=5 11. If y varies directly with x, and y=4 and x=36, what is the rule (equation) for this proportion (variation)? y ļ½ kx 4 ļ½ 36k Divide both 4 36k sides by 36 ļ½ 36 36 1 kļ½ 9 1 yļ½ x 9 12. If y varies directly with x. If y=6 and x=2, what is the value of y when x=5? y ļ½ kx 6 ļ½ 2k 6 2k ļ½ 2 2 k ļ½3 Divide both sides by 2 y ļ½ 3ļ5 y ļ½ 15 13. If y varies directly with x. If y=21 and x=42, what is the value of y when x=52? y ļ½ kx 21 ļ½ 42k Divide both 21 42k ļ½ 42 42 1 kļ½ 2 sides by 42 OR k = .5 y ļ½ .5 ļ 52 y ļ½ 26 14. Sandra uses 1 22 cups of sugar to bake 6 dozen chocolate chip cookies. How many cups of sugar would she need to bake 10 dozen cookies? cups dozen 2.5 x ļ½ 6 10 6 x ļ½ 25 Divide both 1 xļ½4 6 sides by 6 15. Alex rides his bike from school to home in x y 30 minutes traveling 20mph. Today he needs to get home 5 minutes faster. How fast must he ride his bike? k yļ½ x 600 yļ½ 25 k Multiply 20 ļ½ both sides 30 by 30 y ļ½ 24mph 600 ļ½ k 16. The product of the number of i-tunes and video-casts purchased is 32. If 16 video-casts are purchased how many i-tunes can be bought? y ļ½ kx 32 ļ½ 16x Divide both 2ļ½x sides by 16 17. The number of pages Jimbo can read varies directly with the time he spends reading. If he reads 10 pages in 30 minutes, how many pages can he read in 120 minutes? 10 x 30 x ļ½ 1200 Divide ļ½ both mins 30 120 sides by pages x ļ½ 40 pages 30 ļ½ Tomorrow I will have tutoring at 8:15 am. Come in if you would like some more practice with me before your test. ļ½ Study, Study, Study…