Solve x^2 + 4x = 27

1 answer

To solve the equation \(x^2 + 4x = 27\), we first set it to zero by subtracting 27 from both sides:

\[ x^2 + 4x - 27 = 0 \]

Next, we can use the quadratic formula to find the values of \(x\). The quadratic formula is given by:

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

In our equation \(x^2 + 4x - 27 = 0\), the coefficients are:

  • \(a = 1\)
  • \(b = 4\)
  • \(c = -27\)

Now, we can substitute these values into the quadratic formula:

  1. Calculate the discriminant:

\[ b^2 - 4ac = 4^2 - 4 \cdot 1 \cdot (-27) = 16 + 108 = 124 \]

  1. Use the quadratic formula:

\[ x = \frac{-4 \pm \sqrt{124}}{2 \cdot 1} \]

  1. Simplify \(\sqrt{124}\):

\[ \sqrt{124} = \sqrt{4 \cdot 31} = 2\sqrt{31} \]

  1. Substitute back into the formula:

\[ x = \frac{-4 \pm 2\sqrt{31}}{2} \]

  1. Simplify:

\[ x = -2 \pm \sqrt{31} \]

Thus, the solutions for the equation \(x^2 + 4x = 27\) are:

\[ x = -2 + \sqrt{31} \quad \text{and} \quad x = -2 - \sqrt{31} \]