Page 51 - Math Smart - 7

Some children line up in front of a stall during recess. We cannot see how many
Amazing
children there are altogether because there is a tree in the way. The number of
Mathematician
children in the line is unknown.
In about 825 C.E., the
Persian mathematician and
astronomer Muhammed
ibn Miisa ai-Khwarizmi
developed what is now
known as algebra. He
described his method in a
book which he called Hidab
al-jabr wa'l-muqubala which
means 'Putting together and
balancing up'. The word
algebra comes from the word
"al-jabr" In the title of the
We can say that there are n children in the line.
book.
The letter n is used in place of the unknown number.

Three more children join the line. There are now n + 3 children in the line.

Think and Share
What if there are two lines of n children?
We say that there are n + n or 2x n children.
How do you write 2
The simplest way to write this is 2n.
groups of n children
and 3 more?
Example 1

A jar contains some marbles, but we don't know how many.
We can use the variable y to represent the number of
marbles in the jar.

By means 3 times of y or
I have three Identical jars of marbles.
3 groups of y.
I have 3xyor3y marbles.

e