Algebra 2 - Lesson 8-1 and 8-2

Lesson 8-1 and 8-2 Examples:

1) If y varies directly as x, and y = 25 when x = 15, find x when y = 40.

2) Suppose r varies jointly as t and s and inversely as the square of v. When t = 3, s = 18, and v = 5, r = 3.78. Find r when t = 4, s = 12, and v = 4.

3) The amount of hydrogen produced when sodium is added to water is directly proportional to the amount of sodium added. If 92 g of sodium produces 4 g of hydrogen, find the amount of sodium needed to produce 10 g of hydrogen.

4) The surface area of a cylinder varies jointly as the radius and the sum of the radius and height. A cylinder with height 8 cm and radius 4 cm has a surface area of 96*(pi) sq. cm. Find the surface area of a cylinder with radius 3 cm and height of 10 cm.