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Chapter 0 Functions. Chapter Outline. Functions and Their Graphs Some Important Functions The Algebra of Functions Zeros of Functions – The Quadratic Formula and Factoring Exponents and Power Functions Functions and Graphs in Applications. § 0.1. Functions and Their Graphs.
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Chapter Outline • Functions and Their Graphs • Some Important Functions • The Algebra of Functions • Zeros of Functions – The Quadratic Formula and Factoring • Exponents and Power Functions • Functions and Graphs in Applications
§0.1 Functions and Their Graphs
Section Outline • Rational and Irrational Numbers • The Number Line • Open and Closed Intervals • Applications of Functions • Domain of a Function • Graphs of Functions • The Vertical Line Test • Graphing Calculators • Graphs of Equations
The Number Line -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
Open & Closed Intervals -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
Functions in Application EXAMPLE (Response to a Muscle) When a solution of acetylcholine is introduced into the heart muscle of a frog, it diminishes the force with which the muscle contracts. The data from experiments of the biologist A. J. Clark are closely approximated by a function of the form where x is the concentration of acetylcholine (in appropriate units), b is a positive constant that depends on the particular frog, and R(x) is the response of the muscle to the acetylcholine, expressed as a percentage of the maximum possible effect of the drug. (a) Suppose that b = 20. Find the response of the muscle when x = 60. (b) Determine the value of b if R(50) = 60 – that is, if a concentration of x = 50 units produces a 60% response. SOLUTION (a) This is the given function.
Functions in Application CONTINUED Replace b with 20 and x with 60. Simplify the numerator and denominator. Divide. Therefore, when b = 20 and x = 60, R(x) = 75%. (b) This is the given function. Replace x with 50. Replace R(50) with 60.
Functions in Application CONTINUED Simplify the numerator. Multiply both sides by b + 50 and cancel. Distribute on the left side. Subtract 3000 from both sides. Divide both sides by 60. Therefore, when R(50) = 60, b = 33.3.
Functions EXAMPLE If , find f (a - 2). SOLUTION This is the given function. Replace each occurrence of x with a – 2. Evaluate (a – 2)2 = a2 – 4a + 4. Remove parentheses and distribute. Combine like terms.
Graphs of Equations EXAMPLE Is the point (3, 12) on the graph of the function ? SOLUTION This is the given function. Replace x with 3. Replace f (3) with 12. Simplify. false Multiply. Since replacing x with 3 and f(x) with 12 did not yield a true statement in the original function, we conclude that the point (3, 12) is not on the graph of the function.