1. DIRECT and INDIRECT VARIATION ADV130 DIRECT VARIATION: A varies directly as B indicates a direct ratio where 2 things increase or decrease at the same non- zero rate (k). Equation: A = kB When solving you have to find k (constant of proportionality) first and then put it in the equation again to find the missing part.

2. DIRECT and INDIRECT VARIATION ADV130 INDIRECT VARIATION: A varies indirectly or inversely as B if there is a non-zero constant rate (k). Equation A = kBkB When solving you have to find k (constant of proportionality) first and then put it in the equation again to find the missing part.

3. DIRECT and INDIRECT VARIATION ADV130 Answers on following slides. Ex 2) The cost of renting the house is inversely proportional to the number of people who rent. If the cost is $260 per person when 5 people rent, what is the cost when 3 people rent? Ex 1) The area of a circle varies directly as the radius squared. If the area of one circle is 20.41 square inches when the radius is 6.5 inches, what is the area if the radius is 14.25 inches?

4. DIRECT and INDIRECT VARIATION ADV130 20.41 = k(6.5 2 ) k = 3.14 F = 3.14(14.25) = 44.745 ft Ex 1) The area of a circle varies directly as the radius squared. If the area of one circle is 20.41 square inches when the radius is 6.5 inches, what is the area if the radius is 14.25 inches? Area varies directly to radius 2 Area = k(radius 2 )

5. DIRECT and INDIRECT VARIATION ADV130 Ex 2) The cost of renting the house is inversely proportional to the number of people who rent. If the cost is $260 per person when 5 people rent, what is the cost when 3 people rent? Cost = k People $260 = k5k5 Cost varies inversely to people. k = 1300 Cost = 1300 3 = $433.33