Lesson 20

Evaluating Functions over Equal Intervals

  • Let’s evaluate and rewrite expressions.

20.1: Finding Slopes

  1. Find the slope of each line.
    1. The line that passes through (2,2) and (3,6).
    2. The graph of f(x)=\text-2+\frac13x.
  2. Show on the graph where each slope can be seen.
2 comma 2 and 3 comma 6 on a graph of a line 
Graph of line f. y intercept = -2. Slope = the fraction 1 over 3.

 

20.2: Incrementing by One

  1. For the function f(x)=3x+4, evaluate:
    1. f(0) and f(1)
    2. f(100) and f(101)
    3. f(\text-10) and f(\text-9)
    4. f(0.5) and f(1.5)
  2. What do all those pairs of numbers you found have in common?
  3. Write an expression for f(w) and f(w+1).
  4. What would you expect to be the result of subtracting f(w) from f(w+1)?
  5. Subtract f(w) from f(w+1). If you don’t get the answer you predicted, work with a partner to check your algebra.
  6. For the function g(x)=2^x, evaluate:
    1. g(3) and g(4)
    2. g(0) and g(1)
    3. g(\text-1) and g(\text-2)
    4. g(10) and g(11)
  7. What do all those pairs of numbers you found have in common?
  8. Write an expression for g(u) and g(u+1).
  9. What would you expect to be the result of dividing g(u+1) by g(u)?
  10. Divide g(u+1) by g(u). If you don’t get the answer you predicted, work with a partner to check your algebra.

20.3: Rewriting Expressions

  1. Evaluate:
    1. \dfrac{3^5}{3^4}
    2. \dfrac{3^1}{3^0}
    3. \dfrac{3^{\text-1}}{3^{\text-2}}
    4. \dfrac{3^{100}}{3^{99}}
    5. \dfrac{3^{x+1}}{3^x}
  2. Solve for m:
    1. \dfrac{2^m}{2^7}=2
    2. \dfrac{2^{100}}{2^m}=2
    3. \dfrac{2^m}{2^x}=2
  3. Write an equivalent expression using as few terms as possible:
    1. 3(x+1) + 4 - (3x + 4)
    2. 2(x+1) + 5 - (2x + 5)
    3. 2(x+2) + 5 - (2(x+1) + 5)
    4. \text-5(x+1) + 3 - (\text-5x + 3)
    5. \dfrac{5^{x+1}}{5^x}
    6. \dfrac{7^{x+4}}{7^x}

Summary