Ontario 09 Applied (MFM1P) Problem solving with equations I
Lesson

Sometimes we will come across questions that ask us to find an unknown, but the information they give us is not enough to immediately make the solution obvious.

It is up to us to put the pieces together to construct an equation which will make it easier to solve the problem and find the unknown.

The key is to find out what information is important. We can do this by looking for terms such as summinus, or equals and most importantly, by finding out what the question is asking us to solve.

These questions can sometimes look a little more daunting than they are.

#### Example

##### Question 1

The product of $5$5 with the difference of $5$5 from $x$x equals $-15$15. Construct an equation and solve for the value of $x$x.

## Constructing a perimeter

If you are asked to find the perimeter of a shape, you know you need to find the sum of all the lengths. This is still true if the lengths given are expressions.

#### Example

##### Question 2

The perimeter of a triangle is $114$114 cm.

A) Write the perimeter of the triangle in terms of $x$x and simplify.

B) Find $x$x.

### Outcomes

#### 9P.NA2.08

Substitute into algebraic equations and solve for one variable in the first degree