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Precalculus Name: ___________________________ Teacher: _______________ Block: ______ 1.3 The Graphs of Functions: Notes, Examples, and Practice Problems ● The set of all possible inputs (xvalues) of a function is called the domain of a function. ● The set of all the possible outputs (yvalues) of a function is called the range of a function. 2 If I have the function f(x) = x, The domain would be all real numbers because any xvalue input is acceptable, D: (∞, ∞) The range would be all nonnegative numbers because there are no negative yvalue outputs. Zero is included because (0, 0) is a point on the curve. R: [0, ∞). State the domain and range in interval notation. Then find f(0). (Assume the lines of the function end at the end of the graph) 1. 2. D: _______ R:_______ f(0) = ________ D: _______ R:_______ f(0) = ________ A function f is increasing A function f is decreasing A function f is constant on on an interval if, for any x on an interval if, for any x an interval if, for any x and 1 1 1 and x in the interval, and x in the interval, x in the interval, 2 2 2 x < x implies f(x) < f(x). x < x implies f(x) > f(x). f(x) = f(x). 1 2 1 2 1 2 1 2 1 2 Precalculus Name: ___________________________ Teacher: _______________ Block: ______ State the interval on which the graph is increasing, decreasing, or constant. (Assume the lines of the function continue to negative and positive infinity) 3. 4. Increasing: _____________ Increasing: _____________ Decreasing: ____________ Decreasing: ____________ Constant: ______________ Constant: ______________ A function value f(a) is called A function value f(a) is called a relative minimum of f if a relative maximum of f if there exists an interval there exists an interval (x, x) 1 2 (x, x) that contains a such that contains a such that 1 2 that x < x < x implies f(a) ≥ f(x) 1 2 x < x < x implies f(a) ≤ f(x) 1 2 English translation: a point English translation: a point on the graph that has the on a graph that has the lowest yvalue relative to highest yvalue relative to the points around it (valley) the points around it (peak) 3 Given the graph f(x) = x 3x (to the right) The relative maximum will be the point (1, 2). The relative minimum will be the point (1, 2) Precalculus Name: ___________________________ Teacher: _______________ Block: ______ Use the graph to answer the following questions. 5. a. Indicate the interval(s) of which f is increasing. ________ ________________________________________________ b. Indicate the interval(s) of which f is decreasing. ________ ________________________________________________ c. Identify the relative maximum. _________ d. Identify the relative minimum. __________ e. State the domain and range in interval notation._____________________________ 3 Given the function, f(x) = x + x, it is not so easy to estimate the relative maximums and minimums. We are able to approximate these using a graphing calculator. Plug the equation into your calculator and set the window similar to the image to the right. Hit the blue 2nd key then the CALC (TRACE) key. To find the minimum, choose number 3: minimum. It will say “Left Bound?” (similar to finding a zero) You will move the cursor to the left of where you think the relative minimum is and hit ENTER. Now it will say “Right Bound?” Move the cursor to the right of where you think the relative minimum is and hit ENTER. Next it will say “Guess?” Check that your Left and Right Bounds are accurate and hit ENTER. The relative minimum is (.5777, .385). Precalculus Name: ___________________________ Teacher: _______________ Block: ______ To find the maximum, choose number 4: maximum. Repeat the same steps of setting the Left and Right Bound. The relative maximum is (.5777, .385) Use a graphing utility to approximate any relative maximum or minimum values. 3 2 6. f(x) = 2x + 3x 12x Rel. Min. _________ Rel. Max. __________ 2 7. f(x) = x + 7x Rel. Min. _________ Rel. Max. __________ 8. Answer the following: a. the domain of f ________________________ b. the range of f _________________________ c. the xintercepts _______________________ d. the yintercept ________________________ e. intervals on which f is increasing __________ _____________________________________ f. intervals on which f is decreasing ___________ ______________________________________ g. values of x for which f(x) ≤ 0 ______________ ____________________________________ h. the numbers at which f has a relative maximum _____________________________________ i. the relative maxima of f __________________ j. f(2) _________________________________ k. the values of x for which f(x) = 0 ___________
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