Questions: Solve the inequality, and graph the solution set.
(4x+5)/(x-2) ≤ 0
Transcript text: Solve the inequality, and graph the solution set.
\[
\frac{4 x+5}{x-2} \leq 0
\]
Solution
Solution Steps
To solve the inequality \(\frac{4x+5}{x-2} \leq 0\), we need to find the values of \(x\) that make the expression non-positive. This involves finding the critical points where the expression is zero or undefined, and then testing intervals between these points to determine where the inequality holds.
Find Critical Points: Set the numerator equal to zero to find where the expression is zero, and set the denominator equal to zero to find where the expression is undefined.
Test Intervals: Use the critical points to divide the number line into intervals. Test a point from each interval to see if the inequality holds.
Combine Results: Determine the solution set based on the intervals where the inequality is satisfied.
Step 1: Identify Critical Points
To solve the inequality
\[
\frac{4x + 5}{x - 2} \leq 0
\]
we first identify the critical points where the expression is either zero or undefined.
Zero of the numerator: Set the numerator equal to zero.
\[
4x + 5 = 0
\]
Solving for \(x\),
\[
4x = -5 \quad \Rightarrow \quad x = -\frac{5}{4}
\]
Undefined point: Set the denominator equal to zero.
\[
x - 2 = 0
\]
Solving for \(x\),
\[
x = 2
\]
The critical points are \(x = -\frac{5}{4}\) and \(x = 2\).
Step 2: Test Intervals
The critical points divide the number line into three intervals: \((- \infty, -\frac{5}{4})\), \((- \frac{5}{4}, 2)\), and \((2, \infty)\). We will test each interval to determine where the inequality holds.
Interval \((- \infty, -\frac{5}{4})\): Choose \(x = -2\).
\[
\frac{4(-2) + 5}{-2 - 2} = \frac{-8 + 5}{-4} = \frac{-3}{-4} = \frac{3}{4} > 0
\]
The inequality does not hold in this interval.
Interval \((- \frac{5}{4}, 2)\): Choose \(x = 0\).
\[
\frac{4(0) + 5}{0 - 2} = \frac{5}{-2} = -\frac{5}{2} < 0
\]
The inequality holds in this interval.
Interval \((2, \infty)\): Choose \(x = 3\).
\[
\frac{4(3) + 5}{3 - 2} = \frac{12 + 5}{1} = 17 > 0
\]
The inequality does not hold in this interval.
Step 3: Include Critical Points
At \(x = -\frac{5}{4}\), the expression is zero, which satisfies the \(\leq 0\) condition.
At \(x = 2\), the expression is undefined, so it cannot be included in the solution set.