1. Parallel and Perpendicular Lines

2. Sketch a graph: y = 2x + 1
b) What is the slope
& the y-intercept?

3. Slope-Intercept Form: y = mx + b Point-Slope Form:
Linear Equations
Slope-Intercept Form:
y = mx + b
Point-Slope Form:
y – y1 = m(x – x1)
m = slope m = slope
b = y-intercept (x1,y1) – point that the line goes through

4. Parallel Lines
y = mx + b
Parallel Lines have the exact same slope.

5. 1) What is the slope of a line that is parallel to the line y=4x-7?

6. Write the equation of the line parallel to
y = -2x + 1 that has a y-intercept of -4.
4) Write the equation of the line parallel to y = 1/2x – 6 that has a y-intercept of 2.

7. 5) Find the equation of the line parallel to
y=3x+6 passing through the point (-1,9).

8. You try! Write an equation for the lines parallel to
the given lines and passing through the
given points.
6) y = 1/2x – 4; (4,2)
7) y = -2x + 3; (1,2)
8) y = x – 6; (2,5)

9. 9) Are the lines y = -2x + 4
and 5x + 10y = 3 parallel ?

10. 10) Are the lines 3x + y = 4 and -6x + 2y = -1 parallel?

11. Perpendicular Lines y = mx + b
Perpendicular lines have opposite reciprocal slopes.
Also, the product of their slopes is -1.

12. What is the negative reciprocal of each slope?
1 b) -5
c) 1/3 d) -2/5

13. 1) What is the slope of a line that is perpendicular to the line y=-3x – 7 ?

14. Write the equation of the line perpendicular to y = -3x + 1 that has a y-intercept of 5.

15. You try!
Write an equation for the lines perpendicular to the given lines and passing through the
given points.
6) y = -x + 1; (2,-3)
7) y = 2x + 4; (4,2)
8) y = x – 6 ; (0,-1)

16. and -3x + 6y = 1 perpendicular ?
9) Are the lines 2x + y = 4
and -3x + 6y = 1 perpendicular ?

17. 10) Are the lines 3x + 4y = 5 and 6x + 8y = -1 perpendicular?