235 2.3 Functions Use the graph of y = ƒ1x2 to find each function value: (a) ƒ1-22, (b) ƒ102, (c) ƒ112, and (d) ƒ142. See Example 7(d). 73. 4 6 2 0 –2 1 2 3 4 –2 x y –1 74. 6 2 0 –2 1 2 3 4 –2 –1 x y 4 75. 2 0 –4 –2 1 2 3 4 –2 x y –1 4 76. 2 0 –4 –2 1 2 3 4 –2 x y –1 4 An equation that defines y as a function of x is given. (a) Rewrite each equation using function notation ƒ1x2. (b) Find ƒ132. See Example 8. 77. x + 3y = 12 78. x - 4y = 8 79. y + 2x2 = 3 - x 80. y - 3x2 = 2 + x 81. 4x - 3y = 8 82. -2x + 5y = 9 Concept Check Answer each question. 83. The figure shows a portion of the graph of ƒ1x2 = x2 + 3x + 1 and a rectangle with its base on the x-axis and a vertex on the graph. What is the area of the rectangle? (Hint: ƒ10.22 is the height.) 84. The figure shows a portion of the graph of f1x2 = x2 + 3x + 1 and a rectangle with its base on the x-axis and a vertex on the graph. What is the area of the rectangle? (Hint: ƒ10.32 is the height.) 85. The graph of y1 = ƒ1x2 is shown with a display at the bottom. What is ƒ132? 86. The graph of y1 = ƒ1x2 is shown with a display at the bottom. What is ƒ1-22? x y 0.2 0.3 0 y = f(x) x y 0.2 0.3 0 y = f(x) −10 10 10 −10 −10 10 10 −10
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