Name: crystal
Who is asking: Parent
Level: Elementary

Question:
whatis a rule with a variable

Hi Crystal,

I expec that by "a rule with a variable" your child's teacher is looking for a mathematical expression with an unknown in it. For example the area of a rectangle is the length by the width, and for a square the area is the length times the length. For a rectangle you might write this

area = length width

and for a square

area = length²

The first expression has two variables, length and width, and the second has one variable.

For a circle the area is given by

area = pi radius²

This again is a rule with one variable, the radius. The radius is a variable because it depends on the size of the circle but pi is not a variable. Its value is always the same, pi = 3.1416...

Penny

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