The document provides examples of evaluating exponential expressions by substituting values into variables. Example 4a evaluates x4 when x=2, getting 24 or 16. Example 4b evaluates n3 when n=1.5, getting 1.53 or 3.375. The guided practice evaluates x3 when x=8 to get 512, k3 when k=2.5 to get 6.25, and d4 when d=1/3 to get 1/81.

1. EXAMPLE 4 Evaluate powers
Evaluate the expression.
a. x4 when x = 2 b. n3 when n = 1.5
SOLUTION
a. x4 = 24 b. n3 = 1.53
=2 2 2 2 = (1.5)(1.5)(1.5)
= 16 = 3.375

2. GUIDED PRACTICE for Example 4
Evaluate the expression.
9. x3 when x = 8 10. k3 when k = 2.5
ANSWER
9. 512 10. 6.25

3. GUIDED PRACTICE for Example 4
Evaluate the expression.
1
11. d4 when d =
3
ANSWER
11. 1
81