Variables, Operators and Expressions
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A variable is a letter that stands for a number. | For example,
when
we used the letter "b" to stand for the
base of a triangle, we were
using the variable b
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An operator is add, subtract, multiply or divide.
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Note: There are other operators
but we won't go into them now.
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An expression puts variables together with constants and operators. |
For example,
the expression for the area of a triangle is:
| ½ x b x h or |
(b x h) / 2 or |
(b x h)
2 |
where: b = base and h = height
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Usually, multiplication of 2 variables is shown without any
operator, like this:
b h so, if b = 5 and h = 4 then b h = 5 x 4 = 20
Division is shown with a horizontal line, or a slash (/) or the divide symbol (÷):
b h = b h / 2 = b h ÷ 2
2
So... if you have 2 variables "a" and "b", then...
If a = 3 and b = 5, here are some expressions:
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a + b = 3 + 5 = 8 |
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a + 2b =
3 + 2 x 5 =
3 + 10 = 13 <= do the multiply first! |
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ab = 3 x 5 = 15 |
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a - b =
3 - 5 = - 2 <= Remember your negative numbers!
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5a = 5 x 3 = 15 = 3
b 5 5 |
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Now, here is a problem for you:
If a = 7 and b = 5, what is
(8a - 2b) / 2 = ______________
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