Questions: Solve the inequality. Write the solution set in interval notation.
x^2-x-6<0
Choose the correct solution below.
A. (-∞,-2) ∪(3, ∞)
B. -2,3
C. (-2,3)
D. No solution
Transcript text: Solve the inequality. Write the solution set in interval notation.
\[
x^{2}-x-6<0
\]
Choose the correct solution below.
A. $(-\infty,-2) \cup(3, \infty)$
B. $-2,3$
C. $(-2,3)$
D. No solution
Solution
Solution Steps
To solve the inequality \(x^2 - x - 6 < 0\), we first find the roots of the corresponding equation \(x^2 - x - 6 = 0\) using the quadratic formula. These roots will help us determine the intervals to test for the inequality. We then test the intervals between and outside the roots to see where the inequality holds true. Finally, we express the solution set in interval notation.
Step 1: Find the Roots
To solve the inequality \(x^2 - x - 6 < 0\), we first find the roots of the equation \(x^2 - x - 6 = 0\). Using the quadratic formula, we find the roots to be:
\[
x = -2 \quad \text{and} \quad x = 3
\]
Step 2: Determine the Intervals
The roots divide the number line into three intervals:
\((-\infty, -2)\)
\((-2, 3)\)
\((3, \infty)\)
Step 3: Test the Intervals
We need to test each interval to see where the inequality \(x^2 - x - 6 < 0\) holds true.
For the interval \((-\infty, -2)\), choose a test point, e.g., \(x = -3\):
\[
(-3)^2 - (-3) - 6 = 9 + 3 - 6 = 6 \quad (\text{not valid})
\]
For the interval \((-2, 3)\), choose a test point, e.g., \(x = 0\):
\[
0^2 - 0 - 6 = -6 \quad (\text{valid})
\]
For the interval \((3, \infty)\), choose a test point, e.g., \(x = 4\):
\[
4^2 - 4 - 6 = 16 - 4 - 6 = 6 \quad (\text{not valid})
\]
Step 4: Write the Solution Set
The inequality \(x^2 - x - 6 < 0\) holds true in the interval \((-2, 3)\). Therefore, the solution set in interval notation is:
\[
(-2, 3)
\]