Michigan State University - Diagnostic Exam

5.10

  •   Solve the following equation for x.   2x        x
2   - 10 ⋅ 2 + 16 = 0

    a) x = 1 b) x = 1 or 3 c) x =   2
log2-
       
    d) x = 3 e) x = 2 or 8

Solution:

      x             2x        x         2
w  = 2    ⇒    0 = 2  -  10 ⋅ 2 + 16 = w  - 10w +  16
          ⇒    0 = (w - 2)(w -  8)

          ⇒    2, 8 = w = 2x

          ⇒    x = 1, 3

Diagnostic:

If you miss this question please review the method of substitution.

Also, see 3.8: Exponential Equations and 2.3: Equations (Quadratic) .


July 15, 2008