Patterns And Relations Worksheet - Grade 7 Page 14
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46Here are some other algebraic expressions, and their meanings.
In each case, n represents the number.
•
Three more than a number: 3
n or n
3
•
Seven times a number: 7n
7n means 7
n.
•
Eight less than a number: n
8
n
•
A number divided by 20:
20
When we replace a variable with a number in an algebraic
expression, we evaluate the expression. That is, we find the value of
the expression for a particular value of the variable.
Example
Write each algebraic expression in words.
Then evaluate for the value of the variable given.
x
a) 5k
2 for k
3
b) 32
for x
20
4
A Solution
a) 5k
2 means 5 times a number, then add 2.
Replace k with 3 in the expression 5k
2.
Then use the order of operations.
5k
2
5
3
2
Multiply first.
15
2
Add.
17
x
b) 32
means 32 minus a number divided by 4.
4
x
x
Replace x with 20 in the expression 32
.
means x ÷ 4.
4
4
Then use the order of operations.
x
20
32
32
Divide first.
4
4
32
5
Subtract.
27
In the expression 5k
2,
•
5 is the numerical coefficient of the variable.
•
2 is the constant term.
•
k is the variable.
The variable represents any number in a set of numbers.
17
1.3 Algebraic Expressions
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