We can always represent the solution of an inequality using a number line.

For example, let's express the solution of the following inequality using a number line:

5x \geq 30

The variable x is being multiplied by 5. To isolate x, we can perform the opposite operation, which is dividing by 5. So, we divide both sides of the inequality by 5{:}

\begin{align} 5x &\geq 30 \\[5pt] \dfrac{5x}{5} &\geq \dfrac{30}{5} \\[5pt] \dfrac{5x}{5} &\geq 6 \end{align}

Now, we can cancel a common factor of 5 from the numerator and denominator:

\begin{align} \require{cancel} \dfrac{5x}{5} &\geq 6 \\[5pt] \dfrac{\cancel{5}x}{\cancel{5}} &\geq 6 \\[5pt] x &\geq 6 \end{align}

Therefore, the solution is x \geq 6. This solution can be expressed on a number line, as shown below.


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Represent the solution of the inequality k -12 \lt -5 on a number line.

EXPLANATION

To isolate k, we need to perform the opposite of subtracting 12, which is adding 12. Remember to perform the same operation on the right-hand side.

\begin{align} k -12 &\lt -5 \\[5pt] k -12 +12 &\lt -5 +12\\[5pt] k + 0 &\lt 7 \\[5pt] k &\lt 7 \end{align}

Therefore, the solution is k \lt 7. The solution can be expressed on a number line, as shown below.


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Represent the solution of the inequality $10b < 40$ on a number line.

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Represent the solution of the inequality $a + 5 \geq 11$ on a number line.

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Represent the solution of the inequality -6a > -12 on a number line.

EXPLANATION

The variable a is being multiplied by -6. To isolate a, we can perform the opposite operation, which is dividing by -6. So, we divide both sides of the equation by -6.

Remember, when multiplying or dividing by a negative number, we need to flip the inequality:

\begin{align} -6a \,\,&{\color{blue}>}\,\, {-12} \\[5pt] \dfrac{-6a}{-6} \,&{\color{red}< }\,\, \dfrac{-12}{-6} \\[5pt] \dfrac{-6a}{-6} \,&{\color{red}< }\,\, 2 \end{align}

Now, we can cancel a common factor of -6 from both the numerator and denominator.

\begin{align} \require{cancel} \dfrac{-6a}{-6} &< 2 \\[5pt] \dfrac{\cancel{-6}a}{\cancel{-6}} &< 2 \\[5pt] a &< 2 \end{align}

Therefore, the solution is a< 2. The solution can be expressed on a number line, as shown below.


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Represent the solution of the inequality $-4q > -8$ on a number line.

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Represent the solution of the inequality $-\dfrac{x}{3} > -1$ on a number line.

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Represent the solution of the inequality 14 \lt 5x-6 on a number line.

EXPLANATION

First, we apply the addition principle, adding 6 to both sides:

\begin{align} 14 &\lt 5x - 6 \\[5pt] 14 + 6 &\lt 5x - 6 + 6 \\[5pt] 20 &\lt 5x + 0 \\[5pt] 20 &\lt 5x \end{align}

Second, we apply the multiplication principle, dividing both sides by 5{:}

\begin{align} \require{cancel} 20 &\lt 5x \\[5pt] \dfrac{20}{5} &\lt \dfrac{5x}5 \\[5pt] \dfrac{20}5 &\lt \dfrac{\cancel{5}x}{\cancel{5}} \\[5pt] 4 &\lt x \end{align}

Finally, let's swap the left and right-hand sides so that the variable is on the left-hand side. Remember that we also need to flip the inequality. x \gt 4 Therefore, the solution is x \gt 4. The solution can be expressed on a number line, as shown below.


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Represent the solution of the inequality $4x + 2 \le 10$ on a number line.

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Represent the solution of the inequality $-3x + 2 \ge 5$ on a number line.

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Represent the solution of the inequality $7 \le 3x+1$ on a number line.

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b
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e
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