Michigan State University - Diagnostic Exam

2.10

  •   The solution set of the equation √ ------
  x + 1 + 1 = x  is the same as the solution set for which of the following equations.

     

    a) x2 - 3x = 0  b) 3x - 2 =  7  c) x = 0
       
    d)               2
x + 1 + 1 = x   e) x = 2

Diagnostic:

For related exercises see:

Solution:
     √ ------
       x + 1 + 1 = x
     √ ------
⇒      x + 1 = x - 1
     ( √------)2          2
⇒       x + 1   =  (x - 1)
⇒    x + 1 = x2 - 2x + 1

⇒    0 = x2 - 3x

⇒    0 = x (x - 3 ) ⇒   x = 0, 3

Notice that only the solution, x = 3, satisfies the original equation. It follows that √ ------
  x + 1 + 1 = x  is equivalent to 3x-2 = 7

Diagnostic:

If you miss this question please review radical equations.

Also, see 1.18: Expanding Binomials and 1.10: Factoring (Polynomials) .


July 15, 2008