Show that the Fundamental Theorem of Algebra is true for the quadratic polynomial −2x2+4x−9=0


2
𝑥
2
+
4
𝑥

9
=
0
by using the quadratic formula. Which of the following statements accurately describes the solution set?(1 point)
Responses

There are two rational solutions.
There are two rational solutions.

There are two irrational solutions.
There are two irrational solutions.

There are two non-real solutions.
There are two non-real solutions.

There are two identical solutions.

1 answer

To demonstrate the Fundamental Theorem of Algebra for the quadratic polynomial \(-2x^2 + 4x - 9 = 0\), we will use the quadratic formula:

\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]

In this case, we identify the coefficients as follows:

  • \(a = -2\)
  • \(b = 4\)
  • \(c = -9\)

Now, we will calculate the discriminant \(D = b^2 - 4ac\):

\[ D = 4^2 - 4(-2)(-9) = 16 - 72 = 16 - 72 = -56 \]

Since the discriminant \(D\) is negative (\(-56 < 0\)), this indicates that the solutions to the polynomial are non-real (complex). Now we can find the solutions:

Substituting \(a\), \(b\), and \(D\) into the quadratic formula:

\[ x = \frac{-4 \pm \sqrt{-56}}{2(-2)} \]

This simplifies to:

\[ x = \frac{-4 \pm i\sqrt{56}}{-4} \]

Simplifying further:

\[ x = \frac{-4}{-4} \pm \frac{i\sqrt{56}}{-4} = 1 \mp \frac{\sqrt{56}}{4}i \]

Now we can simplify \(\sqrt{56}\):

\[ \sqrt{56} = \sqrt{4 \times 14} = 2\sqrt{14} \]

Thus, the solutions are:

\[ x = 1 \mp \frac{2\sqrt{14}}{4}i = 1 \mp \frac{\sqrt{14}}{2}i \]

This gives us two non-real solutions:

\[ x_1 = 1 + \frac{\sqrt{14}}{2}i \quad \text{and} \quad x_2 = 1 - \frac{\sqrt{14}}{2}i \]

Based on our calculations, the correct statement regarding the solution set for the polynomial \(-2x^2 + 4x - 9 = 0\) is:

There are two non-real solutions.