1. Writing Equations of Parallel and Perpendicular Lines
y-y1=m(x-x1)
Writing Equations of Parallel and Perpendicular Lines
J. Bradford

2. Notes Slide Point-slope form of an equation: y-y1=m(x-x1)
When writing an equation of the line, remember that you need two pieces of information:
1.) Any point on the line
2.) the slope
To find the slope, you must remember two rules.
Parallel lines have the same slope.
Ex: If the slope is -4, the parallel slope will be -4.
Perpendicular lines have negative reciprocal slopes of each other.
Ex: If the given slope is 3, the perpendicular slope will be -1/3.
After you get this information, plug the x and y values from your point and the slope (m) value into the formula and solve for y.

3. Practice Problem #1
Which of the following is an equation of the line that passes through (3,-5) and has a slope parallel to 2?
y=2x-11
y=2x+11
y=3x-1
D. y=3x-11

4. Practice Problem #2
Which of the following is an equation of the line that passes through (2,-1) and is parallel to ?
Y=- ½ x-1
Y=- ½ x+3
Y=- ½ x
D. y=2x+1

5. Practice Problem #3
Write an equation for the line that passes through (-2,-5) and is parallel to the line
y=4x-1.
y=4x-22
y=4x+3
y=4x+18
D. y=4x-3

6. Practice Problem #4
Write an equation of the line that passes through (1,6) and is parallel to the line x+y=-4.
y=x+5
y=-x+7
y=x+7
D. y=-x-7

7. Practice Problem #5
Find the equation of the line parallel to the line whose equation is y=-3x+5 and which passes through the point (3,-2).
Y= -3x-7
y=-3x+11
y=- x-1
D. y= x+3

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