Problem 28

Question

Solve each compound inequality, if possible. Graph the solution set (if one exists) and write it using interval notation. $$ 5 x-3 \geq 2 \text { and } 6 \geq 4 x-3 $$

Step-by-Step Solution

Verified
Answer
The solution is \([1, \frac{9}{4}].\)
1Step 1: Solve the First Inequality
The first inequality is \(5x - 3 \geq 2\). To isolate \(x\), add 3 to both sides: \[5x - 3 + 3 \geq 2 + 3\] which simplifies to \[5x \geq 5\]. Next, divide both sides by 5: \[x \geq 1\].
2Step 2: Solve the Second Inequality
The second inequality is \(6 \geq 4x - 3\). First, add 3 to both sides: \[6 + 3 \geq 4x - 3 + 3\] which simplifies to \[9 \geq 4x\]. Now, divide both sides by 4: \[\frac{9}{4} \geq x\] or equivalently, \(x \leq \frac{9}{4}\).
3Step 3: Find the Overlapping Solution Set
The solution to the compound inequality requires both conditions to be true simultaneously. So, combine \(x \geq 1\) and \(x \leq \frac{9}{4}\). The overlapping solution is \(1 \leq x \leq \frac{9}{4}\).
4Step 4: Graph the Solution Set
On a number line, plot a closed circle at 1 and a closed circle at \(\frac{9}{4}\). Shade the region between 1 and \(\frac{9}{4}\) to denote all values in this interval are part of the solution.
5Step 5: Express in Interval Notation
The interval notation for the solution set is \([1, \frac{9}{4}]\). This notation indicates that 1 and \(\frac{9}{4}\) are included in the solution set.

Key Concepts

Solving InequalitiesInterval NotationGraph Solution Sets
Solving Inequalities
In mathematics, inequalities involve the use of signs like \( >, <, \geq, \leq \) to show one side is larger or smaller than the other. When solving inequalities, the goal is to find all values of a variable that make the inequality true.

For example, consider the inequality \(5x - 3 \geq 2\). To solve it, we aim to isolate \(x\). Start by adding 3 to both sides to cancel out the negative 3, which gives us \(5x \geq 5\).

Now, divide both sides by 5 to isolate \(x\), resulting in \(x \geq 1\). Follow similar steps for the second inequality \(6 \geq 4x - 3\): add 3 to both sides, resulting in \(9 \geq 4x\), then divide by 4 to find \(x \leq \frac{9}{4}\).

When working with compound inequalities, finding a common solution set or the overlap of the solutions is key. Here, both conditions \(x \geq 1\) and \(x \leq \frac{9}{4}\) must be satisfied at the same time. Hence, the solution is the interval \(1 \leq x \leq \frac{9}{4}\).
Interval Notation
Interval notation is a concise way to express a range of values, typically used with inequalities. It involves brackets and parentheses to indicate whether endpoints are included or excluded.

In our exercise, the solution set \(1 \leq x \leq \frac{9}{4}\) can be expressed using interval notation as \([1, \frac{9}{4}]\).

The square brackets \([\) mean that the endpoints 1 and \(\frac{9}{4}\) are included in the solution set. If an endpoint was not included, a parenthesis \(()\) would be used instead. For instance, \((1, \frac{9}{4}]\) would indicate 1 is not part of the solution.

Interval notation streamlines the expression and can easily be interpreted on a number line.
Graph Solution Sets
Graphing solution sets visually represents the range of solutions for an inequality on a number line. It’s an intuitive method to showcase which values satisfy the given conditions.

To graph \(1 \leq x \leq \frac{9}{4}\), a closed circle is drawn at 1 and \(\frac{9}{4}\) to show that these numbers are included in the solution.

The section between these endpoints is shaded to indicate all numbers within this range are part of the solution set.
  • Closed circles represent included endpoints (use square brackets in interval notation).
  • Open circles represent excluded endpoints (use parentheses in interval notation).


Graphs make it easier to understand the scope of solutions and confirm that both inequalities overlap correctly in a compound inequality scenario.