Solve for k.

k2–3k–4=0
Write each solution as an integer, proper fraction, or improper fraction in simplest form. If there are multiple solutions, separate them with commas.
k=

1 answer

To solve the quadratic equation \( k^2 - 3k - 4 = 0 \), we can use the quadratic formula:

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

In this equation, \( a = 1 \), \( b = -3 \), and \( c = -4 \).

First, we need to calculate the discriminant \( b^2 - 4ac \):

\[ b^2 - 4ac = (-3)^2 - 4(1)(-4) = 9 + 16 = 25 \]

Now we substitute back into the quadratic formula:

\[ k = \frac{-(-3) \pm \sqrt{25}}{2(1)} = \frac{3 \pm 5}{2} \]

This gives us two solutions:

  1. When using the plus sign:

\[ k = \frac{3 + 5}{2} = \frac{8}{2} = 4 \]

  1. When using the minus sign:

\[ k = \frac{3 - 5}{2} = \frac{-2}{2} = -1 \]

Thus, the solutions are

\[ k = 4, -1 \]

The final answer is:

\[ k = 4, -1 \]