Year 9 Interactive Maths - Second Edition

Equations Containing Brackets

To solve an equation containing brackets, we may proceed as follows:

Remove the brackets by expanding according to the Distributive Law.  Collect the pronumeral terms on the left-hand side of the equation and the numerical terms on the right-hand side of the equation by doing the same operations(s) to both sides of the equation. Then solve the equation for the pronumeral by performing additional operations, if necessary.

Example 13

Solution:

Example 14

Solution:

Problem Solving

Example 15

Find the width of a rectangular paddock whose length is 90 m and perimeter is 340 m.

Solution:

So, the width of the paddock is 80 m.

Example 16

A rectangular paddock is twice as long as it is wide, and has a perimeter of 42 m. Find its dimensions.

Solution:

We are given that:

So, the length of the paddock is 14 m and the width is 7 m.