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Intermediate Algebra – 1

HFCC Math Lab

SLOPE – INTERCEPT AND POINT-SLOPE FORMS OF THE LINE

THE EQUATION OF A LINE

Goal I.

Use the slope-intercept form of the line to write the equation of a non-vertical line

A. given its y-intercept and slope

B. given its y-intercept and another point on the line

Goal II. Write the equation of a horizontal line through a given point.

Goal III. Use the point-slope form of the line to write the equation of a non vertical line

A. given its slope and a point on the line

B. given two points on the line

Goal IV. Write the equation of a vertical line through a given point.

Goal V.

Given the equation of a line, find the slope and the y-intercept.

TERMINOLOGY

m = slope of the line

b = the y-intercept (where the line crosses the y-axis)

( , ), ( ,

x y

x y

)

two given points on the line ( may be the intercept points)

1

1

2

2

I.

SLOPE-INTERCEPT FORM OF A LINE: The equation of the line with slope m

and y-intercept b is given by y = mx + b

Examples:

A.

1. Find the equation of the line with slope 5 and y-intercept 7.

m = 5, b = 7; y = mx + b

Therefore, y = 5x + 7 is the equation of the line.

2

2.

Find the equation of the line with slope

and y-intercept 0.

3

2

m =

, b = 0; y = mx + b

3

Therefore,

2

y

x

0

3

2

y

x

is the equation of the line.

3

Revised 11/09

1

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Parent category: Education