Year 7 Interactive Maths - Second Edition

Equations

We know that:

Clearly, both 6 + 9 and 3 × 5 have the same value of 15.  So we can express this as the following equation:

Similarly, a number sentence such as

is an equation because:

Note:

Using Pronumerals in Equations

Clearly, the number sentence

is an equation.

If the value of the pronumeral x is 5, then x can take the place of 5; and we can write this equation as

This is an equation containing the pronumeral x.  The value of the pronumeral x is 5.

Example 1

Describe each of the following equations in words:

Solution:

Example 2

Write an equation to represent each of the following statements:
a.  When I add 6 to a number, the answer is 15.
b.  When I subtract 5 from a number, the answer is 18.
c.  When I multiply a number by 4, the answer is 20.
d.  When I divide a number by 3, the answer is 9.

Solution:

Key Term

equation