1. Direct variation Y = mX

2. Y X 1 2 3 4 5 6 7 8 9 10 number of sessions 40 35 30 25 20 15 10 5 0 Cost ($) The cost of private gymnastic lessons (y) varies directly with the number of sessions (x) as shown in the graph. Write a direct variation equation. Identify the constant of variation and interpret its meaning. Constant of variation (slope) 10 1 Equation y = 10x Meaning: Each session costs $10

3. Y X 2 4 6 8 10 cat’s age in years 40 35 30 25 20 15 10 5 0 Human years age A 3 year old cat is often considered to be 15 in human years. Assume that the equivalent age in human years (y) varies directly with its age as a cat (x). Write and solve a direct variation equation to determine the human age of a cat that is 6 years old. y = mx 15 = m(3) y = 5x y = 5 · 6 y = 30 y = 30 a cat that is 6 years old is equivalent to a human that is 30 years old

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5. Y X 1 2 3 4 5 6 7 8 9 10 number of sessions 40 35 30 25 20 15 10 5 0 Cost ($) The cost of private gymnastic lessons (y) varies directly with the number of sessions (x) as shown in the graph. Write a direct variation equation. Identify the constant of variation and interpret its meaning. Constant of variation (slope) Equation Meaning: Each session costs

6. Y X 2 4 6 8 10 cat’s age in years 40 35 30 25 20 15 10 5 0 Human years age A 3 year old cat is often considered to be 15 in human years. Assume that the equivalent age in human years (y) varies directly with its age as a cat (x). Write and solve a direct variation equation to determine the human age of a cat that is 6 years old. y = mx ______ = m(____) y = ______x y = _____ · _______ y = ________ y = _______ a cat that is 6 years old is equivalent to a human that is _______ years old