and press ENTER. Move the cursor close to the x-intercept using the left arrow key and press ENTER. Repeat these steps for each x-intercept. The x-intercepts are (2, 0) and (3, 0) as shown in the graphs to the right. The y-intercept is found by graphing the function and pressing TRACE 0 ENTER. As shown on the graph, the y-intercept for y x2 x 6 is (0, 6). The x-value of the vertex can be found using the vertex formula. In this case, a 1 and b 1, so b 2a 1 2 . To fi nd the vertex on the graph, press TRACE, type 1/2, and press ENTER. The vertex is shown as (0.5, 6.25) on the graph. Remember, you can convert the coordinates of the vertex to fractions. Go to the home screen by pressing 2nd MODE. To display the x-value of the vertex, press X, T, , n MATH ENTER ENTER. To display the y-value of the vertex, press ALPHA I MATH ENTER ENTER. The vertex is then a1 2 , 25 4 b. Find the x-intercepts, y-intercept, and vertex using a graphing calculator. 1) y x2 2x 2 2) y x2 4x 5 3) y (x 1)2 4 4) y x2 4 5) y x2 6x 9 6) y x2 8x 19 ANSWERS TO YOU TRY EXERCISES 1) g(x) x2 1 x y 5 V(0, 1) 5 5 5 2) x y 5 V(4, 0) 8 2 g(x) (x 4)2 5 3) x y 5 5 5 5 g(x) (x 2)2 4) x-ints: (0, 0), (2, 0); y-int: (0, 0) (x) 2(x 1)2 2 x 5 5 5 5 (1, 2) www.mhhe.com/messersmith SECTION 10.5 Quadratic Functions and Their Graphs 663
messersmith_power_intermediate_algebra_1e_ch4_7_10
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