Inequalities · Meet inequalities · 1.3

Graph on a number line.

An inequality’s solutions form a ray on the number line. A closed (filled) circle marks an included boundary (≤, ≥); an open circle marks an excluded one (<, >). The arrow shades every value that works.

01 / THE IDEA

See it work.

Watch the method

Graph on a number line

Closed circle = included (≤/≥); open = excluded (</>); arrow shows direction.

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circle at 4,  >\text{circle at } 4,\; >
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Read the graph

A closed circle includes the value (≤/≥); an open circle excludes it. The arrow shows the direction.

x>4x > 4

On the number line

Shade the solutions.

A open circle excludes 4; the arrow points to every value that works.

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02 / YOUR TURN

Practice until it feels automatic.

Your turn

Solve for x.

Type the solution, e.g. x < 4 (you can write <= for ≤).

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— / WHY IT WORKS

The idea underneath.

Circle + arrow

Read the circle (open/closed) for the symbol type and the arrow for the direction.

Why it works

Filled dot = “and this one too”.

03 / WORKED EXAMPLES

From easy to tricky.

EX 1easy

A number line has a closed circle at -1 and the arrow points right. Write the inequality.

1

Read the graph

A closed circle includes the value (≤/≥); an open circle excludes it. The arrow shows the direction. x ≥ -1

EX 2medium

A number line has an open circle at -4 and the arrow points left. Write the inequality.

1

Read the graph

A closed circle includes the value (≤/≥); an open circle excludes it. The arrow shows the direction. x < -4

EX 3hard

A number line has an open circle at -5 and the arrow points right. Write the inequality.

1

Read the graph

A closed circle includes the value (≤/≥); an open circle excludes it. The arrow shows the direction. x > -5

04 / COMMON TRAPS

Where students slip.

Trap

Filling a circle for < or >.

Fix

Strict inequalities use an OPEN circle.

Trap

Shading the wrong way.

Fix

x > n shades to the right; x < n to the left.

05 / QUIZ

Test yourself.

The Test

12 problems across three tiers. Auto-graded on submit. Hints and a full walkthrough on every question. Your work is saved on this device — sign in to keep it across devices.

0/12Answered
How to answerType just the value. Formatting won't trip you up — we ignore spaces, capital letters, commas, and subscript style, so t₁ = 5, d = 3 and t1=5,d=3 both count. For a list of numbers, separate them with commas (e.g. 3, 10, 17).
Core

Core (4)

C1

A number line has an open circle at 1 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
C2

A number line has an open circle at 6 and the arrow points left. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
C3

A number line has a closed circle at 6 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
C4

A number line has an open circle at 3 and the arrow points left. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
Apply

Apply (4)

A1

A number line has a closed circle at 4 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
A2

A number line has a closed circle at -5 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
A3

A number line has a closed circle at -5 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
A4

A number line has a closed circle at -5 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
Extension

Extension (4)

E1

A number line has a closed circle at 2 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
E2

A number line has an open circle at 1 and the arrow points left. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
E3

A number line has an open circle at 1 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.
E4

A number line has a closed circle at -4 and the arrow points right. Write the inequality.

Need a hint?
  • Closed circle → ≤ or ≥.
  • Arrow right → >; arrow left → <.