Complex Numbers Unit Test

16 of 2516 of 25 Items

Question
One of the solutions to the equation x3+5x2+10x+50=0
is −5
. Find the full solution set. Which of the following options correctly describes the solution set?

Option #1: It has one real solution and two non-real solutions.

Option #2: It has one non-real solution and two real solutions.

Option #3: It has three real solutions.

(1 point)
Option #

1 answer

To find the full solution set for the polynomial equation \(x^3 + 5x^2 + 10x + 50 = 0\) given that one of the solutions is \(x = -5\), we can perform synthetic division to factor the polynomial.

  1. Perform synthetic division with \(x + 5\):

    Set \(x = -5\) for synthetic division:

    -5 |  1   5   10   50
       |      -5     0   -50
       ---------------------
         1   0   10    0
    

    The result is \(x^2 + 10\) with a remainder of 0.

  2. Factor the equation:

    Now, we have: \[ x^3 + 5x^2 + 10x + 50 = (x + 5)(x^2 + 10) \]

  3. Solve \(x^2 + 10 = 0\):

    \[ x^2 = -10 \]

    The solutions are: \[ x = \sqrt{-10} = \pm i\sqrt{10} \]

  4. Full solution set:

    The solution set includes:

    • One real solution: \(x = -5\)
    • Two non-real solutions: \(x = i\sqrt{10}\) and \(x = -i\sqrt{10}\)
  5. Choose the correct option:

    The correct option that describes this solution set is:

Option #1: It has one real solution and two non-real solutions.

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