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There's a funny looking set of lines that we sometimes
use in math: |
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(stuff) |
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What the lines mean is: |
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"All right, we know
you're in there... Come on out with NO minus
sign." |
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These lines are called: |
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Absolute Value
Notation
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If whatever's inside the straight lines doesn't have a
minus sign, |
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nothing happens. |
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If it does have a "-" sign, it drops it before it
comes out |
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(maybe it also raises its hands). |
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So: |
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| -5 | = 5
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| 23
| = 23 |
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-3.14 | = 3.14 |
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Example: |
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So
what happens if we have ... |
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| 3 - 7 |
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These lines kind of look like parenthesis ( )
don't they? |
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Well, they work just like parenthesis too! |
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Do whatever's
inside them first. |
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Then lose any minus sign on the way
out. |
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So: |
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3 - 7 | = | - 4 | = 4
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Example: |
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How
about this one ... |
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- | 5 - 8 | |
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OK, the lines are a type of parenthesis, |
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so you do
what's inside them first: |
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- | - 3 | |
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Then the thing left inside comes out without the minus
sign: |
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-
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3
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But then the negative
sign waiting outside sticks to
it: |
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-
3
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Example: |
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OK,
Now let's do ... |
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-
| 5 - 7 |3
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Step
1: |
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- | - 2 |3
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Step
2: |
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- 23 |
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Step
3: |
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-
(2 × 2 ×
2)3
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Step
4: |
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-
8
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Example: |
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OK,
Let's go really crazy, |
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how
about ... |
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- | 3 - 7 ||6 - 9|
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Step 1:
Do the stuff inside the absolute value
lines: |
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- | - 4 ||- 3|
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Step 2:
Bring the numbers out of their own lines without
their "-" signs. |
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Any "-" signs waiting outside then stick to
them. |
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- 43 |
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Step 3: Apply the exponent: |
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- (4 ×
4 × 4) |
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64 |
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Step 4: Bring the number out without the "-"
sign. |
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64 |
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copyright 2005 Bruce Kirkpatrick |
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