REAL WORLD EXAMPLES OF f (x) The real world—round, fast-paced, expensive— relies on functions! --The circumference of a circle, C(r), depends on its radius, r. C(r) = 2 п r --The area of a circle, A(r), depends on its radius, r. A(r) = п r 2 --The distance, D(r), from home to work depends on the time, t, spent driving at an average speed of r miles an hour. D(r) = r t --The value, V(t), of an investment, P,with an annual return of r %, depends on t years. V(t) = P r t.

1) Let g(x) = - 5 x + 2. Evaluate each of the following: a) g(- 1) = ___________ b) g(- 2) = ___________ c) g(0) = ___________ d) g(5) = ___________ - 5(- 1) + 2 = = 7 - 5(- 2) + 2 = = (0) + 2 = = 2 - 5(5) + 2 = = - 23

2) Let f(x) = 2 x + 2. Evaluate each of the following: a) f(- 3) = ___________ b) f(6) = ___________ c) f(- 1) = ___________ d) f(4) = ___________ 2(- 3) + 2 = = - 4 2(6) + 2 = = 14 2(- 1) + 2 = = 0 2(4) + 2 = = 10

3) Let g(x) = x x – 1. Evaluate each of the following: a) g(- 4) = ___________ b) g(8) = ___________ c) g(- 1) = ___________ d) g(1) = ___________ (- 4) 2 + 4(- 4) – 1 = 16 – 16 – 1 = - 1 (8) 2 + 4(8) – 1 = – 1 = 95 (- 1) 2 + 4(- 1) – 1 = 1 – 4 – 1 = - 4 (1) 2 + 4(1) – 1 = – 1 = 4

4) Let f(x) = 3x 2 – 5 x. Evaluate each of the following: a) f(2) = ___________ b) f(- 8) = ___________ c) f(7) = ___________ d) f(- 1) = ___________ 3(2) 2 – 5(2) = 3(4) – 10 = 12 – 10 = 2 3(- 8) 2 – 5(- 8) = 3(64) + 40 = = 232 3(7) 2 – 5(7) = 3(49) – 35 = 147 – 35 = 112 3(- 1) 2 – 5(- 1) = 3(1) + 5 = = 8

5) Suppose f(x) = 4 x – 2. Determine x such that: a) f(x) = 18 ___________ b) f(x) = 0 ___________ 4 x – 2 = 18 4 x = 20 x = 5 4 x – 2 = 0 4 x = 2 x = 2 / 4 = ½ =.5

5) Suppose f(x) = 4 x – 2. Determine x such that: c) f(x) = - 2 ___________ d) f(x) = 12 ___________ 4 x – 2 = x = 0 x = 0 4 x – 2 = 12 4 x = 14 x = 14 / 4 = 7 / 2 = 3.5

6) Suppose n(x) = 7 x + 4. Determine x such that: a) n(x) = 39 ___________ b) n(x) = 0 ___________ 7 x + 4 = 39 7 x = 35 x = 5 7 x + 4 = 0 7 x = - 4 x = - 4 / 7 = -.571

6) Suppose n(x) = 7 x + 4. Determine x such that: c) n(x) = 4 ___________ d) n(x) = 13 ___________ 7 x + 4 = 4 7 x = 0 x = 0 7 x + 4 = 13 7 x = 9 x = 9 / 7 = 1.286

7) Suppose g(x) = - 5 x + 6. Determine x such that: a) g(x) = 21 ___________ b) g(x) = 0 ___________ - 5 x + 6 = x = 15 x = x + 6 = x = - 6 x = 6 / 5 = 1.2

7) Suppose g(x) = - 5 x + 6. Determine x such that: c) g(x) = - 6 ___________ d) g(x) = 14 ___________ - 5 x + 6 = x = - 12 x = 12 / 5 = x + 6 = x = 8 x = - 8 / 5 = - 1.6

8) Suppose g(x) = - 3 x + 8. Determine x such that: a) g(x) = 14 ___________ b) g(x) = 0 ___________ - 3 x + 8 = x = 6 x = x + 8 = x = - 8 x = 8 / 3 = 2.67

8) Suppose g(x) = - 3 x + 8. Determine x such that: c) g(x) = - 14 ___________ d) g(x) = 15 ___________ - 3 x + 8 = x = - 22 x = 22 / 3 = x + 8 = x = 7 x = - 7 / 3 =

9) Evaluate the following expressions given the functions below: a) g(10) = ___________ b) f(3) = ___________ g(x) = - 3 x + 1 f(x) = x j(x) = 2 x (10) + 1 = = - 29 c) h(- 2) = __________ d) j(7) = __________ (3) = =16 2(7) + 9 = = 23

9) Evaluate the following expressions given the functions below: g(x) = - 3 x + 1 f(x) = x j(x) = 2 x + 9 e) Find x if g(x) = 16. ____ f) Find x if h(x) = - 2. ____ g) Find x if f(x) = 23. ____ - 3 x + 1 = x = 15 x = x = 12 x = - 6 x = 23 x 2 = 16 x = 4

10) Translate the following statements into coordinate points: a) f(-1) = 1___________ b) h(2) = 7___________ c) g(1) = - 1___________ d) k(3) = 9___________ (- 1, 1) (2, 7) (1, - 1) (3, 9)

Given this graph of the function f(x): Find: 11) a.) f(- 4) = ____ b.) f(0) = ____ c.) f(3) = ____ d.) f(- 5) = ____ e.) x when f(x) = 2 _______ f.) x when f(x) = 0 _______ and 2 0

12) a.) If f(x) = 7 x – 3, then find f(0). ____ b.) If f(t) = | 5 t |, then find f(2). ____ c.) If g(x) = x x – 6, then find g(1). ____ d.) If f(b) = 3 b, then find f(3). ____

13) Denise decides to study abroad in France. She has to exchange her dollars for Euros. The following function describes the exchange rate between dollars and Euros: f(d) =.75 d Find f(200). _____________ f (200) =.75(200) =

14) The profit from selling s number of t- shirts is described by the following function: p(s) = 8 s – 500 Find p(70) __________ p(70) = 8(70) – 500 p(70) = 560 –

15) The value of a car is given by the following function: v(t) = 20,000(.90)t Find v(1) __________ v(1) = 20,000(.90)(1) v(1) =

16) Daniel’s income for the fall semester is described by the following function: f(h) = 1, h Find f(320) __________ f(320) = (320) f(320) =

17) Felix’s total credit card balance is described by the following function: c(p) = p(1.30) Find c(2500) __________ c(2500) = 2500(1.30) c(2500) =

18) The study time per credit hour is described by the following function: s(c) = 3 c Find s(15) __________ s(15) = 3(15) = 45 45

19) The total amount of gas money is determined by the following function: c(g) = Find c($ 3.00) _________ 60

20) The number of Facebook friends you make d days after arriving on campus is described by the following function: f(d) = 2 d Find f(7) _________ f(7) = 2(7) = 14 14