1) Direct Variation 2) Joint Variation 3) Inverse Variation
Direct Variation Can be expressed in the form y=kx K in this equation is called constant of variation Slope of a direct variation = constant of variation. As x increases, y increases or decreases at a constant rate (y varies directly as x)
If you know [y varies directly as x] and one set of values, you can use a proportion to find the other set of corresponding values.
Joint Variation When 1 quantity varies directly as the product of two or more other quantities. Y varies jointly as x and z if there is some number k such that y=kxz
If you know y varies jointly as x and z and one set of values, you can use a proportion to find the other set of corresponding values.
Suppose y varies jointly as x and z. Find y when x=8 and z=3, if y=16 when z=2 and x =5. Joint Variation Cross Multiply Divide by 10 Substitute numbers into the Joint Variation
Inverse Variation As one quantity increases, the other quantity decreases. If there is a nonzero constant k, xy=k or y= Speed and time vary inversely with each other because when you travel somewhere, as your speed increases, the time it takes you to get there decreases.