Download presentation

1
**5.3 Writing Linear Equations given Two points**

Objective Write an equation of a line given two points of the line. Steps: Find the slope. y - y m = 2 1 x - x 2 1

2
**Find the y-intercept. Substitute the slope m and the**

coordinates of one of the points into the slope- intercept form, y = mx + b, and solve for the y-intercept b. 3. Write an equation of the line. Substitute the slope m and the y-intercept b into the slope-intercept form, y = mx + b.

3
EXAMPLE Write an equation of the line that passes through the points (1, -3) and (3, 5). (x1,y1) (x2,y2) 5 – (-3) 8 1. Find the slope. m = m = 4 m = 3 – 1 2 2. Find the y-intercept. Choose one of the ordered pairs. (Either ordered pair will result in the same y-intercept) Using (1, -3) Using (3, 5) y = mx + b y = mx + b -3 = 4(1) + b 5 = 4(3) + b -3 = 4 + b 5 = 12 + b -7 = b -7 = b

4
**Substitute the slope and the y-intercept into y = mx + b**

m = and b = -7 y = 4x - 7

5
EXAMPLE Your Turn 1. Find the equation of a line passing through the points (1, 6) and (3, -4). Steps 1) Find slope 2) Find y-intercept b 3) Write equation m = -5 b = 11 Y = -5x +11

6
**Two different nonvertical lines are perpendicular if and**

only if their slopes are opposite reciprocals of each other. Negative Reciprocal Examples Number Negative Reciprocal 3 -2

7
EXAMPLE Write the equation of a line perpendicular to the line y = -2x + 2 and passing through (6, 8). m = -2. Perpendicular slope = ½. Replace ½ into y =mx +b then find b Use (6,8) for (x,y) 8 = ½(6) + b 8 = 3 + b 5 = b The equation of the perpendicular line is y = ½ x + 5.

8
EXAMPLE Try this. Find the equation of a line perpendicular to the equation y = -1/3x – 2 and through the point (-2, -3). m = 3 y = mx + b -3 = 3(-2) + b -3 = -6 + b 3 = b y = 3x + 3

9
Objective 2 2 Modeling a real-life situation. A camp program charges a registration fee and a daily amount. If the total bill for one camper was $338 for 12 days and the total bill for another camper was $506 for 19 days, how much will the bill be for a camper who enrolls for 30 days? Identify the independent variable (x) and the dependent variable (y). Since part of the bill depends on the number of days, the independent variable is the number of days. Write the two ordered pairs. (12, 338) and (19, 506) The registration fee is the y-intercept (b). This value is not know.

10
**Find the slope and the y-intercept.**

(12, 338) (19, 506) m = m = 24 y = mx + b y = 24x + 50 This means that the camper pays $24 each day and a registration fee of $50. 338 = 24(12) + b 338 = b 50 = b If a camper is there for 30 days, find the cost. y = 24(30) + 50 y = y = $770

Similar presentations

Presentation is loading. Please wait....

OK

2.4 Write Equations of Lines

2.4 Write Equations of Lines

© 2018 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google

Ppt on acid-base titrations Ppt on types of parallelograms rectangle Ppt on responsive web design Download ppt on soil erosion and conservation Ppt on computer system for class 9 Ppt on introduction to object-oriented programming php Elementary ppt on cells Ppt on transportation in plants for class 7 Ppt on sports day dallas Ppt on area of plane figures formulas