Understanding Perpendicular Lines

This video tutorial from Friendly Math 101 covers how to write equations of perpendicular lines. It begins with an introduction to key terms such as point-slope form and slope-intercept form. The concept of opposite reciprocals is explained, which is crucial for understanding perpendicular slopes. The tutorial provides three examples, demonstrating how to write equations of lines that are perpendicular to given lines and pass through specific points. Each example is solved step-by-step, showing the conversion from point-slope form to slope-intercept form. The lesson concludes with an invitation for viewers to ask questions and subscribe for more tutorials.

What is the point-slope form of an equation?

• x = my + b

• y = mx + b

• y - y1 = m(x - x1)

• ax + by = c

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CCSS.8.EE.B.5

What does the term 'opposite reciprocal' mean in the context of slopes?

• Only flipping the fraction

• Multiplying the slope by -1

• Changing the sign and flipping the fraction

• Only changing the sign

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CCSS.8.EE.B.5

In the first example, what is the opposite reciprocal of the slope 2/3?

• -3/2

• 2/3

• -2/3

• 3/2

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How do you convert an equation from point-slope form to slope-intercept form?

• Add the slope to both sides

• Multiply both sides by the slope

• Distribute and solve for y

• Subtract the y-intercept from both sides

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CCSS.8.EE.B.6

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What is the slope-intercept form of the equation from the first example?

• y = 2/3x - 1

• y = -2/3x + 1

• y = 3/2x - 9

• y = -3/2x + 9

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CCSS.8.EE.B.5

In the second example, what is the opposite reciprocal of the slope -4?

• 4

• -1/4

• 1/4

• -4

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CCSS.8.EE.B.6

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What is the first step in writing an equation in slope-intercept form?

• Add the y-intercept

• Distribute to remove parentheses

• Multiply by the slope

• Subtract the x-intercept

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CCSS.8.EE.B.6

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What is the slope-intercept form of the equation from the second example?

• y = 1/4x + 11/4

• y = 1/4x - 11/4

• y = -1/4x + 11/4

• y = -1/4x - 11/4

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CCSS.8.EE.B.5

In the final example, what is the opposite reciprocal of the slope -1/2?

• 1/2

• -2

• 2

• -1/2

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CCSS.8.EE.B.6

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What is the slope-intercept form of the equation from the final example?

• y = 2x - 20

• y = 2x + 20

• y = -2x + 20

• y = -2x - 20

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CCSS.8.EE.B.6

CCSS.8.F.A.3