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1 2. c + b. Warm Up Evaluate each expression for a = 2, b = –3, and c = 8. 1. a + 3 c 2. ab – c 3. 26. –14. 1. 4. 4 c – b. 35. 5. b a + c. 17. Solve each equation for y. y = – 2 x + 3. 6. 2 x + y = 3. 7. – x + 3 y = – 6.
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1 2 c + b Warm Up Evaluate each expression for a = 2, b = –3, and c = 8. 1. a + 3c 2.ab – c 3. 26 –14 1 4. 4c – b 35 5. ba + c 17 Solve each equation for y. y = –2x + 3 6. 2x + y = 3 7. –x + 3y = –6 y = 2x – 4 8. 4x– 2y = 8
4-6: Functions A function is a special type of relation that pairs each domain value with exactly one range value. In other words, for every input (x value), there is exactly one output (y value).
Example 1: Identifying Functions Give the domain and range of the relation. Tell whether the relation is a function. Explain. {(3, –2), (5, –1), (4, 0), (3, 1)} D: {3, 5, 4} Even though 3 is in the domain twice, it is written only once when you are giving the domain. R: {–2, –1, 0, 1} The relation is not a function. Each domain value does not have exactly one range value. The domain value 3 is paired with the range values –2 and 1.
Additional Example 1B: Identifying Functions Give the domain and range of the relation. Tell whether the relation is a function. Explain. X Y Use the arrows to determine which domain values correspond to each range value. –4 2 –8 D: {–4, –8, 4, 5} 1 4 5 R: {2, 1} This relation is a function. Each domain value is paired with exactly one range value.
Example 1c Give the domain and range of each relation. Tell whether the relation is a function and explain. X Y a. {(8, 2), (–4, 1), (–6, 2),(1, 9)} b. D: {–6, –4, 1, 8} R: {1, 2, 9} D: {2, 3, 4} R: {–5, –4, –3} The relation is a function. Each domain value is paired with exactly one range value. The relation is not a function. The domain value 2 is paired with both –5 and –4.
Mini Lesson Quiz: Part I 3. Give the domain and range of the relation. Tell whether the relation is a function. Explain. X Y D: {5, 10, 15}; R: {2, 4, 6, 8}; The relation is not a function since 5 is paired with 2 and 4.
Example 2A The three points below form a straight line, thus this appears to be the graph of a linear function. Use the vertical line test on the graph. No vertical line will intersect the graph more than once. The equation –3x + 2 = y represents a function.
Example 2B The points below appear to form a V-shaped graph. Draw two rays from (0, 2) to show all the ordered pairs that satisfy the function. Draw arrowheads on the end of each ray. Use the vertical line test on the graph. No vertical line will intersect the graph more than once. The equation y = |x| + 2represents a function.
Reading Math Functions can be named with any letter; f, g, and h are the most common. You read f(6) as “f of 6,” and g(2) as “g of 2.”
Evaluation of Functions: Example 4 Evaluate the function for the given input values. For h(c) = 2c – 1, find h(c) when c = 1 and when c = –3. h(c) = 2c– 1 h(c) = 2c– 1 h(1) = 2(1) – 1 h(–3) = 2(–3) – 1 = 2– 1 = –6– 1 = 1 = –7
Example 4b Evaluate each function for the given input values. 4. For g(t) = find g(t) when t = 20 and when t = –12. g(20) = 2 g(–12) = –6 5. For f(x) = 6x –1,find f(x) when x = 3.5 and when x = –5. f(3.5) = 20 f(–5) = –31