Copyright © 2011 Pearson, Inc. 1.5 Parametric Relations and Inverses
Copyright © 2011 Pearson, Inc. Slide What you’ll learn about Relations Defined Parametrically Inverse Relations and Inverse Functions … and why Some functions and graphs can best be defined parametrically, while some others can be best understood as inverses of functions we already know.
Copyright © 2011 Pearson, Inc. Slide Relations Defined Parametrically Another natural way to define functions or, more generally, relations, is to define both elements of the ordered pair (x, y) in terms of another variable t, called a parameter.
Copyright © 2011 Pearson, Inc. Slide Example Defining a Function Parametrically
Copyright © 2011 Pearson, Inc. Slide Solution tx = t – 1y = t 2 + 2(x, y) –3–411(–4, 11) –2–36(–3, 6) –1–23(–2, 3) 0–12(–1, 2) 103(0, 3) 216(1, 6) 3211(2, 11)
Copyright © 2011 Pearson, Inc. Slide Example Defining a Function Parametrically
Copyright © 2011 Pearson, Inc. Slide Solution
Copyright © 2011 Pearson, Inc. Slide Inverse Relation The ordered pair (a,b) is in a relation if and only if the pair (b,a) is in the inverse relation.
Copyright © 2011 Pearson, Inc. Slide Horizontal Line Test The inverse of a relation is a function if and only if each horizontal line intersects the graph of the original relation in at most one point.
Copyright © 2011 Pearson, Inc. Slide Inverse Function
Copyright © 2011 Pearson, Inc. Slide Example Finding an Inverse Function Algebraically
Copyright © 2011 Pearson, Inc. Slide Solution
Copyright © 2011 Pearson, Inc. Slide The Inverse Reflection Principle The points (a, b) and (b, a) in the coordinate plane are symmetric with respect to the line y = x. The points (a, b) and (b, a) are reflections of each other across the line y = x.
Copyright © 2011 Pearson, Inc. Slide Example Finding an Inverse Function Graphically Graph y = x 3 – 4 and its inverse. Is y a one-to-one function?
Copyright © 2011 Pearson, Inc. Slide Solution Graph y = x 3 – 4 and its inverse. Is y a one-to-one function? To find an equation for the inverse, interchange x and y, then solve for y.
Copyright © 2011 Pearson, Inc. Slide Solution Note that y 1 and y 2 are reflections of each other about the line y = x. Since the graph passes the horizontal and vertical line tests, f is a one-to-one function.
Copyright © 2011 Pearson, Inc. Slide The Inverse Composition Rule
Copyright © 2011 Pearson, Inc. Slide Example Verifying Inverse Functions
Copyright © 2011 Pearson, Inc. Slide Solution
Copyright © 2011 Pearson, Inc. Slide How to Find an Inverse Function Algebraically
Copyright © 2011 Pearson, Inc. Slide Quick Review
Copyright © 2011 Pearson, Inc. Slide Quick Review Solutions