Point Slope Form Standard Form

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Point Slope FormStandard Form
Writing Equations of Lines
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Point Slope Form
Variable
Variable
y y1 m(x x1)
Slope
(x1, y1)
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Steps

• Write the equation
• Determine the slope
• Substitute slope for m
• Substitute values from a point for x1 and y1
• Eliminate any double signs (i.e. -, --, etc.)

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Why does the point-slope form work?
Find the slope between (x1, y1) and (x, y).
Reflexive property
Point-Slope Form
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Write the equation of the line with slope 3 and
passing through the point (1, 5).
Use Point-Slope Form
y y1 m(x x1)
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Write the equation of the line with slope ¾ and
passing through the point (-5, 3).
Use Point-Slope Form
y y1 m(x x1)
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Write the equation of the line with slope -2/3
and passing through the point (2, -4).
y y1 m(x x1)
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Write the equation of the line passing through
the points (-2, 6) and (3, -1).
Find the slope
y y1 m(x x1)
let's use (3, -1)
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Write the equation of the line passing through
the points (4, 3) and (6, 8).
Find the slope
y y1 m(x x1)
let's use (4, 3)
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Write the equation of the line passing through
the points (4, -3) and (-7, -1).
Find the slope
y y1 m(x x1)
let's use (4, -3)
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Standard Form
Constant
Both Cant Be 0
Integer When Possible
Any Constant
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Steps

• Basically, solve for C
• Get the x and y on one side of the
• Get the constant on the other side of the

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Convert y 3x 2 to standard form.
multiply both sides by -1
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Convert y 6776x to standard form.
multiply both sides by -4
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Convert y 6776x to standard form.
multiply both sides by 7
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Convert y 6776x to standard form.
multiply both sides by -2
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Convert y 6776x to standard form.
multiply both sides by 15
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More on Slope

• Parallel lines have the same slope
• Perpendicular lines have opposite reciprocal
  slopes

Parallel Lines
Perpendicular Lines
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Write the equation of the line parallel the line
4x 5y 7 that passes through the point (-3, 7)
What is the slope of the given line?
y y1 m(x x1)
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Write the equation of the line perpendicular the
line 3x 2y 9 that passes through the point
(2, 5)
What is the slope of the given line?
y y1 m(x x1)