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Math · Grade 6 Math

Chapter 6: Equations and Inequalities

Inequalities on a Number Line

When the answer is a stretch, not a point.

Lesson
5
Time
About 17 minutes
0 of 7 done

Step 1: Let's Learn

Read it, or press Listen and follow the words.

x > 5 is true for 6, for 5.1, and for a million. An inequality has no single answer.

Drawing it

Mark 5, then shade every number to the right of it.

Open or closed

x > 5 leaves 5 out, so the circle is open. x ≥ 5 includes it, so the circle is filled.

Reading the symbol

The wide end faces the larger side. In x > 5 the wide end faces x, so x is the bigger one.

Drawing the solution

For n > 5, draw an open circle at 5 and shade everything to the right. The open circle means 5 itself is not included. For n ≥ 5, fill the circle in. The drawing encodes both the range and whether the endpoint counts.

Which way to shade

Shade the side containing the numbers that make the inequality true. Test one: is 6 > 5? Yes, so shade towards 6. Testing a single point is more reliable than trying to remember which symbol points which way.

Solving works the same way

For n + 3 > 8, subtract 3 from both sides to get n > 5. Inequalities are solved by the same balance reasoning as equations. One caution for later: multiplying or dividing both sides by a negative flips the direction of the symbol.

Context can cut the range down

If n is a number of people, n > 5 really means 6, 7, 8 and so on — not 5.5. The mathematics allows every real number above 5, but the situation may only allow whole ones. Saying so is part of a complete answer.

Step 2: Try It Yourself

Tap and try it out.

Place a value and check whether it satisfies the inequality.
-10-9-8-7-6-5-4-3-2-1012345678910

6

Step 3: Watch an Example

One step at a time.

Watch Leo Draw x < 3

Leo represents x < 3 on a number line.

  1. Step 1

    He marks 3 on the line.

Step 4: Your Turn

Practice makes it stick.

The Ride

Problem 1 of 2

You must be over 8 to ride. Is 8 allowed? Answer 1 for yes, 0 for no.

The Smallest Whole

Problem 2 of 2

What is the smallest whole number that satisfies x > 8?

True or Not

1 of 4

Does 7 satisfy x > 5? Answer 1 for yes, 0 for no.

2 of 4

Does 5 satisfy x > 5? Answer 1 for yes, 0 for no.

3 of 4

Smallest whole number satisfying x > 2?

4 of 4

Largest whole number satisfying x < 6?

Step 5: Quick Check

Show what you know.

Question 1 of 1

Smallest whole number satisfying x > 11?

What You Learned

  • An inequality is satisfied by a whole stretch of numbers, not one.
  • An open circle leaves the endpoint out; a filled circle includes it.
  • The wide end of the symbol faces the larger side.