1 / 14

Geometry

Geometry. Lesson 3 – 4 Equations of Lines. Objective: Write an equation of a line given information about the graph. Solve problems by writing equations. Equation Forms. Slope-Intercept Form y = mx + b m – slope b – y-intercept Point-Slope Form y – y 1 = m(x – x 1 )

saari
Télécharger la présentation

Geometry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Geometry Lesson 3 – 4 Equations of Lines Objective: Write an equation of a line given information about the graph. Solve problems by writing equations.

  2. Equation Forms • Slope-Intercept Form • y = mx + b • m – slope • b – y-intercept • Point-Slope Form • y – y1 = m(x – x1) • m – slope • (x1, y1)

  3. Write an equation in slope-intercept form of the line with slope 3 and y-intercept of –2. Then graph the line. • y = mx + b • y = 3x – 2 • Graphing: • Put a dot on the y-intercept • (0, 3) • Use slope (rise/run) to find more points. • Up 3 over 1

  4. Write an equation in slope-intercept form of the line with slope ½ and y-intercept of 8. Then graph the line. • y = ½ x + 8 • Graphing • Graph (0, 8) • Up 1 over 2 Don’t have to go by 2’s

  5. Write an equation in point-slope form of the line with slope –3/4 that contains (-2,5). Then graph. • y – y1 = m(x – x1) (x – (-2)) Graphing: plot point, then use slope

  6. Write an equation in point-slope of the line with slope of 4 that contains (-3, -6). Then graph. • y + 6 = 4(x + 3)

  7. Method 1: Find the slope m = 2 Use slope-intercept form Pick one of the points 3 = 2(0) + b b = 3 y = 2x + 3 Method 2: Find the slope m = 2 Use point-slope form Pick one of the points y – 3 = 2(x – 0) Solve for y to put in slope-intercept form. y – 3 = 2(x – 0) y – 3 = 2x y = 2x + 3 Write an equation of the line through each points in slope-intercept form(0, 3) and (-2, -1) You may use either method

  8. Write an equation of the line through each points in slope-intercept form(-2, 4) & (8, 10)

  9. Write an equation of the line through (-2, 6) & (5, 6) in slope-intercept form. • Find the slope • m = 0 (horizontal line) • 6 = 0(-2) + b • 6 = b • y = 0x + 6 • y = 6 Make sure you simplify. Do not leave 0x or 0

  10. Horizontal & Vertical Lines • When an equation only has 1 variable it is either a horizontal or vertical line • The equation tells you how to graph. • y = 6 • The line goes through the axis of the variable given. • A horizontal line at 6 through the y-axis.

  11. y = 3 x = 6 x = -1 5 = y -9 = x x = 0 y = 0 Tell whether the following is a horizontal or vertical line. horizontal horizontal vertical vertical Vertical (y-axis) vertical Horizontal X-axis

  12. Write an equation in slope-intercept form for a line perpendicular to the line y = -3x + 2 through (4, 0). • Step 1: Identify slope for new equation • m = 1/3 (because of perpendicular) • Write new equation with new slope and point.

  13. Write an equation is slope-intercept form for a line parallel to y = (-3/4)x + 3 containing (-3, 6) • Step 1: Identify slope for new equation • (-3/4) same slope since parallel • Write new equation with new slope and point.

  14. Homework • Pg. 200 1 – 12 all, 14 – 40 E

More Related