8.1.1 Variation Functions - Worksheet
Example 1: Given: y varies directly as x . Write and graph each direct variation function. 1. y = 6 when x = 3 2. y = 45 when x = − 5
3. y = 54 when x = 4.5
Example 2: 4. The wavelength λ of a wave of a certain frequency varies directly as the velocity v of the wave, and λ = 60 ft when v = 15 ft/s. Find λ when v = 3 ft/s.
5. The dollar amount d that Julia earns varies directly as the number of hours t that she works, and d = $116.25 when t = 15 h. Find t when d = $178.25.
Example 3: 6. The volume V of a rectangular prism of a particular height varies jointly as the length l and the width w , and V = 224 ft 3 when l = 8 ft and w = 4 ft. Find l when V = 210 ft 3 and w = 5 ft.
7. The total cost C of electricity for a particular light bulb varies jointly as the time t that the light bulb is used and the cost k per kilowatt-hour, and C = 12 ₵ when t = 50 h and k = 6 ₵ per kilowatt- hour. Find C to the nearest cent when t = 30 h and k = 8 ₵ per kilowatt-hour.
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