2.4 MORE ABOUT LINEAR EQUATIONS

SLOPE AND LINES

POINT – SLOPE FORM

EXAMPLE: WRITING AN EQUATION GIVEN A POINT AND THE SLOPE A line passes through with slope

What is an equation of the line?

5,2 3

5

EXAMPLE: WRITING AN EQUATION GIVEN A POINT AND THE SLOPE A line passes through with slope

What is an equation of the line?

7, 1 3

WRITING AN EQUATION GIVEN TWO POINTS

1. Find the slope

2. Substitute the slope and one point into the point-slope form

2 1

2 1

y ym

x x

1 1y y m x x

EXAMPLE

A line passes through (3, 2) and (5, 8). What is an equation of the line in point-slope form?

EXAMPLE

A line passes through (- 5, 0) and (0, 7). What is an equation of the line in point-slope form?

STANDARD FORM

WRITING AN EQUATION IN STANDARD FORM WITH INTEGER COEFFICIENTS

EXAMPLE: WRITE THE EQUATION IN STANDARD FORM. USE INTEGER COEFFICIENTS.

35

4y x

GRAPHING AN EQUATION

The quickest way to graph a line is to:1. Find the x – intercept by setting y = 02. Find the y – intercept by setting x = 03. Plot the intercepts4. Draw the line

EXAMPLE: WHAT ARE THE INTERCEPTS OF THE EQUATION? GRAPH THE EQUATION.

3 5 15x y

PARALLEL AND PERPENDICULAR LINES

WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR LINES

1. Find the appropriate slope2. Use the given point and point – slope form

to write the equation of the line

EXAMPLE: WRITE THE EQUATION OF THE LINE IN SLOPE – INTERCEPT FORM.The line parallel to

and through

6 2y x

1, 3

EXAMPLE: WRITE THE EQUATION OF THE LINE IN SLOPE – INTERCEPT FORM.

The line perpendicular to

and through

24

3y x

8,5

EXAMPLE: WRITE THE EQUATION OF THE LINE IN SLOPE – INTERCEPT FORM.

The line parallel to

and through

4 2 7x y

4, 2

EXAMPLE: WRITE THE EQUATION OF THE LINE IN SLOPE – INTERCEPT FORM.

The line perpendicular to

and through

21

3y x

0,6

HOMEWORK

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