Michigan State University - Diagnostic Exam

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4.5

  •   The solutions of the equation x2 + 4x + 5 = 0 are x =(?).

    a) -1, 5 b) 1, 4 c) -2 ± i d) -4 ± 2i e) 2.4 ± 4i

Solution:

2 2 x + 4x + 5 = 0 ⇒ x + 4x + 4 = - 1 ⇒ (x + 2 )2 = - 1 ⇒ x = - 2 ± i

Diagnostic:

See 2.2: Equations (Quadratic) and 4.4: Complex Numbers .

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July 15, 2008