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In the previous lesson you learned that
if Jane is 3 years older than Joe, you can express Jane's age as n +
3. But in this lesson you will find her actual age if you know
Joe's age. If Joe is 10, then you also know that Jane is 10 + 3 or 13
years old. See, it's easy! So let's get going!
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Let's see how to substitute values into variable expressions!
(In other words, let's solve the expression, or put a number in
place of the letter!)
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Let's use different values for the
variable, and the expression is
n + 5
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Step One: |
Step Two: (n +
5) |
Step Three: |
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If the variable is = |
then substitute it in the
expressions |
and solve! |
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8 |
n
+ 5 =
8
+ 5 |
8 +
5 = 13 |
|
2 |
n
+ 5 =
2 + 5 |
2 +
5 = 7 |
|
7 |
n
+ 5 =
7 + 5 |
7
+ 5 = 12 |
|
10 |
n
+ 5 =
10 + 5 |
10 + 5 = 12 |
|
0 |
n
+ 5 =
0 + 5 |
0
+ 5 = 5 |
OK, that was easy; let's try some more difficult ones,
and in slightly different forms. Remember, a variable can be any
symbol, not just "n".
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Step One:
If the variable is |
Step Two:
find the value of: |
Step Three:
Solve |
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y = 7 |
y - 3 |
7 - 3 = 4 |
| n = 4 |
2n (remember
this is multiplying) |
2 (4) = 8 |
| m = 10 |
m ÷2 |
10 ÷2 = 5 |
| r = 0 |
8 - r |
8 - 0 = 8 |
| a = 50 |
3a (remember this is also
multiplying) |
3(50) = 150 |
Now what would you like to do?
Go to
Lesson Part 2? (using Order of Operations)
or go to
Practice 1?
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