Algebra 4 6 Slope Intercept Form And Parallel

Algebra 4. 6 Slope Intercept Form And Parallel Lines

You have already learned an easy method of graphing that uses only the y-intercept (b) and the slope (m).

Let’s review. .

Slope-Intercept Form y = mx + b slope y-intercept rise run where the line crosses the y axis

Converting to Slope-Intercept Form (y = mx + b) Convert: 4 x – 5 y = 15 -4 x -5 y = -4 x + 15 -5 -5

Converting to Slope-Intercept Form (y = mx + b) Convert: 4 x – 5 y = 15 -4 x -5 y = -4 x + 15 -5 -5 Now let’s graph this equation.

Graph the y-intercept y The y intercept of the line is -3. Plot the point (0, -3) on the y axis. . x (0, -3)

Using the slope to find more points The slope of the line is or Rise 4 Run 5 y . . . (5, 1) (10, 5) x (0, -3) From the y intercept of (0, -3) rise 4, run 5, plot, repeat. Then connect for the line.

Parallel Lines • Parallel lines in the same plane do not intersect • Horizontal lines are parallel to other horizontal lines • Vertical lines are parallel to other vertical lines • Sloped lines (uphill and downhill) are parallel to each other if they have the same slope

Horizontal Lines y Horizontal lines are all parallel to each other. y=5 y=3 x y = -2 y = -6 Horizontal lines all have a slope of 0.

Vertical Lines Vertical lines are all parallel to each other. x = -6 y x = -2 x=3 x=5 x Vertical lines all have a slope that is UNDEFINED.

Sloped Lines y = 2 x + 4 y Sloped lines are all parallel to each other if they have the same slope. y = 2 x + 1 y = 2 x - 2 y = 2 x - 5 x

Sloped Lines y Sloped lines are all parallel to each other if they have the same slope. y = -½x + 4 x y = -½x -3 y = -½x - 4

Check for Understanding Which of the following lines are parallel? (Hint: convert to slopeintercept form and compare slopes) a) b) c) 3 y = -9 x – 5 2 y – 6 x = -5 12 x + 4 y = 1 Answer: Lines a and c are parallel. They both have a slope of -3.

Homework pg. 245 #46 -55, 60 -61, 66 -68 pg. 247 Quiz 2 all