Use the quadratic formula to solve the quadratic equation 2x2−9x+11=0

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1 answer

To solve the quadratic equation \(2x^2 - 9x + 11 = 0\) using the quadratic formula, we first identify the coefficients \(a\), \(b\), and \(c\) in the standard form of the quadratic equation \(ax^2 + bx + c = 0\).

Here:

  • \(a = 2\)
  • \(b = -9\)
  • \(c = 11\)

The quadratic formula is given by:

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

Now, we will calculate \(b^2 - 4ac\):

\[ b^2 = (-9)^2 = 81 \] \[ 4ac = 4 \cdot 2 \cdot 11 = 88 \] \[ b^2 - 4ac = 81 - 88 = -7 \]

Since \(b^2 - 4ac\) is negative, we have no real solutions, but we can find complex solutions.

Now substituting the values into the quadratic formula:

\[ x = \frac{-(-9) \pm \sqrt{-7}}{2 \cdot 2} = \frac{9 \pm \sqrt{-7}}{4} \]

Now we express \(\sqrt{-7}\) in terms of \(i\):

\[ \sqrt{-7} = i\sqrt{7} \]

Substituting this back, we get:

\[ x = \frac{9 \pm i\sqrt{7}}{4} \]

Thus, the solutions to the equation \(2x^2 - 9x + 11 = 0\) are:

\[ x = \frac{9 + i\sqrt{7}}{4} \quad \text{and} \quad x = \frac{9 - i\sqrt{7}}{4} \]