You can use this presentation to introduce students in how to write linear equations given the slope and the y-intercept. This is the first case in writing linear equations.
2. 5.1 WRITING LINEAR EQUATIONS IN
SLOPE-INTERCEPT FORM
During this lesson, you will learn how to write an equation of a line using as
information, the slope (m) and the y-intercept (b). To do this, you need to remember
the slope-intercept form of a linear equation:
𝒚 = 𝒎𝒙 + 𝒃
You also need to remember that there are different ways to represent the slope of a
line:
𝒎 =
∆𝒚
∆𝒙
=
𝒄𝒉𝒂𝒏𝒈𝒆 𝒊𝒏 𝒚
𝒄𝒉𝒂𝒏𝒈𝒆 𝒊𝒏 𝒙
=
𝒚 𝟐 − 𝒚 𝟏
𝒙 𝟐 − 𝒙 𝟏
The y-intercept is the point in the y-axis were the graph of the line is crossing.
3. 5.1 WRITING LINEAR EQUATIONS IN
SLOPE-INTERCEPT FORM
Below, you will see the most typical examples in writing equations of a line using the
slope and y-intercept. In some cases, you only need to replace the given values in the
slope-intercept form of the linear equation.
a. Write an equation of the line whose slope is – 2 and whose y-intercept is 5.
b. Write an equatons of the line whose slope is −
2
5
and whose y-intercept is – 10 .
4. 5.1 WRITING LINEAR EQUATIONS IN
SLOPE-INTERCEPT FORM
Information can be presented in different ways in the process of writing an equation of a
line. Some examples can be seen below:
c. Write an equation of a line passing through 0, −4 that has a change in y of 5 and a
change in x of 3.
d. Write an equation of a line passing through 0, 12 that has ∆𝑥 = 4 𝑎𝑛𝑑 ∆𝑦 = −8.
6. 5.1 WRITING LINEAR EQUATIONS IN
SLOPE-INTERCEPT FORM
Another way to write equations of a line is by reading information from a graph. In this
particular situation, you must follow these steps:
• Identify the y-intercept in the graph.
• Identify the slope of the line, by finding ∆𝑥 𝑎𝑛𝑑 ∆𝑦, to determine the slope. This can
be done by identifying “the triangle” in the line.
Examples: Write an equation of the line shown in the graph.
1.
