Cls. 5 Mathematics | Solving equations using number line

Description

 Using the number line

A number line is a straight line with a zero point in the middle.  On either side of zero, Negative and positive numbers are listed on either side of the zero and go on indefinitely.  Negative numbers are to the left of zero while positive numbers are to the right of zero.  The value of numbers increases as you move to the right.  The value decreases as you move to the left.

We can use a number line in math to find the answer to addition and subtraction questions.

In Algebra we can use a number line to solve addition and subtraction problems involving like terms.

Example:  Simplify 5(6y -3) + 3(6 – 5y)

• • • Step 1:  Open the brackets

= 5 x 6y -5 x 3 + 3 x 6 – 3 x 5y

= 30y – 15 + 18 -15y

• • • Step 2: Identify the operation sign for each term

= + 30y – 15 + 18 -15y

Note: If the sign before the first term is not indicated, always use the plus sign)

• • • Step 3: Put like terms together starting from left to right

= 30y – 15y – 15 + 18

= 15y -15 + 18

• Remember you can use the number line to add or subtract like terms.
• In our simplified problem above the only like terms that have not been solved are

– 15 + 18 (i.e. negative fifteen plus 18)

You can therefore use the number line to finish working out the answer as follows:

On the number line, start at –15.  Because 18 has a positive sign before it (i.e. +18), we will move 18 steps to the right.

Quiz