Lesson 20
Evaluating Functions over Equal Intervals
- Let’s evaluate and rewrite expressions.
20.1: Finding Slopes
- Find the slope of each line.
- The line that passes through (2,2) and (3,6).
- The graph of f(x)=\text-2+\frac13x.
- Show on the graph where each slope can be seen.
20.2: Incrementing by One
- For the function f(x)=3x+4,
evaluate:
- f(0) and f(1)
- f(100) and f(101)
- f(\text-10) and f(\text-9)
- f(0.5) and f(1.5)
- What do all those pairs of numbers you found have in common?
- Write an expression for f(w) and f(w+1).
- What would you expect to be the result of subtracting f(w) from f(w+1)?
- Subtract f(w) from f(w+1). If you don’t get the answer you predicted, work with a partner to check your algebra.
- For the function g(x)=2^x,
evaluate:
- g(3) and g(4)
- g(0) and g(1)
- g(\text-1) and g(\text-2)
- g(10) and g(11)
- What do all those pairs of numbers you found have in common?
- Write an expression for g(u) and g(u+1).
- What would you expect to be the result of dividing g(u+1) by g(u)?
- 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
- Evaluate:
- \dfrac{3^5}{3^4}
- \dfrac{3^1}{3^0}
- \dfrac{3^{\text-1}}{3^{\text-2}}
- \dfrac{3^{100}}{3^{99}}
- \dfrac{3^{x+1}}{3^x}
- Solve for m:
- \dfrac{2^m}{2^7}=2
- \dfrac{2^{100}}{2^m}=2
- \dfrac{2^m}{2^x}=2
- Write an equivalent expression using as few terms as possible:
- 3(x+1) + 4 - (3x + 4)
- 2(x+1) + 5 - (2x + 5)
- 2(x+2) + 5 - (2(x+1) + 5)
- \text-5(x+1) + 3 - (\text-5x + 3)
- \dfrac{5^{x+1}}{5^x}
- \dfrac{7^{x+4}}{7^x}