Algebra 1 : How to find the equation of a perpendicular line

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #91 : Perpendicular Lines

Suppose a line has an x-intercept of one and a y-intercept of two. What is the equation of the perpendicular line which pass through the point ?

Possible Answers:

Correct answer:

Explanation:

Write the points that correspond to the x and y-intercepts given in the problem.

X-intercept of one: 

Y-intercept of two: 

Find the slope of this line connected with these points.

The slope is negative two. The slope of the perpendicular line is the negative reciprocal of this slope.

Write the slope-intercept form.

Substitute the perpendicular slope with the point that this line will pass through.

Solve for the y-intercept, .

Subtract nine halves on both sides.

Simplify both sides.

With the perpendicular slope and the y-intercept, write the equation of the line.

The answer is:

Example Question #331 : Functions And Lines

What is the slope of a line perpendicular to the line with the following equation?

Possible Answers:

Answer cannot be determined from this information.

Correct answer:

Explanation:

Step 1: get the line into y = mx +b format to find the slope m:

Next, we need to remember that perpendicular lines have slopes that are negative reciprocals. Find the negative reciprocal of :

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