Absolute value is the distance a number is from 0 on a number line.
📌 The most important rule:
✅ Absolute value is always non-negative (never negative)
We write absolute value using bars:
∣x∣
⭐ Key Idea
Absolute value tells you how far a number is from 0, not what direction.
So:
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∣5∣ = 5
-
∣−5∣ = 5
Both are 5 units away from 0, just on opposite sides of the number line.
🔢 Absolute Value on a Number Line
Think of the number line:
… -3, -2, -1, 0, 1, 2, 3 …
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−3 is 3 steps from 0 → ∣−3∣= 3
-
2 is 2 steps from 0 → ∣2∣ = 2
🧠 Absolute Value Rule (Simple)
For any number x:
∣x∣ = {x if x ≥ 0
{−x if x < 0
Meaning:
-
If the number is positive or 0, keep it the same.
-
If the number is negative, make it positive.
Example:
-
∣−12∣ = 12
-
∣0∣ = 0
🔥 Why Absolute Value Matters (Real Life)
Absolute value is used whenever you care about the size of a difference but not the direction.
Examples:
✅ Temperature change
-
If it goes from 3° to -2°, the change is:
∣3 − (−2)∣ = ∣5∣ = 5
✅ Distance
-
Distance between -7 and 4 is:
∣−7 − 4∣ = ∣−11∣ = 11
✅ Error / how far off you are
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If you predicted 50 but the answer is 46:
∣50 − 46∣ = 4