Download presentation

Presentation is loading. Please wait.

Published byRose Ryan Modified over 7 years ago

1
Unit 3 Part 2 Writing Equations Ax + By = C (standard form) y = mx + b (slope – intercept form)

2
y = mx + b is a form of an equation What is the equation of a line that has a slope of ½ and a y-intercept of -3 ? y = mx + b y = ½ x – 3 Don’t forget the ‘x’

3
Try these on your own. What is the equation of a line that has a slope of 2 and a y-intercept of -1 ? y = 2x – 1 What is the equation of a line that has a slope of ¾ and a y-intercept of 2 ? y = ¾ x + 2

4
y = mx + b Write the equation of the line whose slope is 2 and contains the point ( 1, 5). 1 st substitute into the equation. y = mx + b 5 = (2)(1) + b 5 = 2 + b -2 -2 3 = b and ‘m’ = 2 y = 2x + 3

5
y = mx + b Write the equation of the line whose slope is 3 and contains the point ( 2, 8). 1 st substitute into the equation. y = mx + b 8 = (3)(2) + b 8 = 6 + b -6 -6 2 = b and ‘m’ = 3 y = 3x + 2

6
y = mx + b Write the equation of the line whose slope is -2 and contains the point ( 4, -9). 1 st substitute into the equation. y = mx + b -9 = (-2)(4) + b -9 = -8 + b +8 +8 -1 = b and ‘m’ = -2 y = -2x – 1

7
y = mx + b Write the equation of the line whose slope is ½ and contains the point ( - 4, -3). 1 st substitute into the equation. y = mx + b -3 = ( ½ )(- 4) + b -3 = -2 + b +2 +2 -1 = b and ‘m’ = ½ y = ½ x – 1

8
Write the equation of the line that contains these two points. ( 1, 3) ( 2, 6) 1 st Calculate the slope Now substitute y = mx + b 3 = 3(1) + b 3 = 3 + b -3 -3 0 = b y = 3x + 0 y = 3x 3 – 6 -3 1 – 2 -1 m = = = + 3

9
Write the equation of the line that contains these two points. ( 3, 4) ( 5, 10) 1 st Calculate the slope Now substitute y = mx + b 4 = 3(3) + b 4 = 9 + b -9 -9 -5 = b y = 3x – 5 4 – 10 -6 3 – 5 -2 m = = = + 3

10
Write the equation of the line that contains these two points. ( 4, -2) ( -8, 7) 1 st Calculate the slope Now substitute y = mx + b -2 = - ¾ (4) + b -2 = -3 + b +3 +3 +1 = b y = - ¾ x + 1 -2 – 7 -9 4 – (-8) 12 m = = = - 3 4

11
Write the equation of the line that contains these two points. ( -6, -3) ( 0,-5) 1 st Calculate the slope Now substitute y = mx + b -3 = - ⅓ (-6) + b -3 = 2 + b -2 -2 -5 = b y = - ⅓ x – 5 -3 –(-5) 2 -6 – 0 -6 m = = = - 1 3

12
Write the equation of the line that contains these two points. ( -2, -4) ( 2, -2) 1 st Calculate the slope Now substitute y = mx + b -4 = ½(-2) + b -4 = -1 + b +1 +1 -3 = b y = ½ x – 3 -4 – (-2) -2 -2 – 2 -4 m = = = + ½

13
y – y = m ( x – x) Formula Write the equation of the line that has a slope of 2 and passes through the point ( -6, 4). 1 st substitute into the formula. y – y = m ( x – x) y – 4 = 2 ( x – (-6)) y – 4 = 2 ( x + 6 ) y – 4 = 2x + 12 + 4 + 4 y = 2x + 16 Can you do it ? Let’s see!

14
y – y = m ( x – x) Formula Write the equation of the line that has a slope of -3 and passes through the point ( 1, -2). 1 st substitute into the formula. y – y = m ( x – x) y – (-2) = -3 ( x – 1) y + 2 = -3 ( x – 1 ) y + 2 = -3x +3 - 2 - 2 y = -3x + 1

15
y – y = m ( x – x) Formula Write the equation of the line that has a slope of ½ and passes through the point ( 4, -3). 1 st substitute into the formula. y – y = m ( x – x) y – (-3) = ½ ( x – 4) y + 3 = ½ ( x – 4 ) y + 3 = ½x - 2 - 3 - 3 y = ½ x - 5

16
y – y = m ( x – x) Formula Write the equation of the line that has a slope of -¾ and passes through the point ( 8, -1). 1 st substitute into the formula. y – y = m ( x – x) y – (-1) = -¾ ( x – 8) y + 1 = -¾ ( x – 8 ) y + 1 = -¾ x + 6 - 1 - 1 y = -¾ x + 5

17
y – y = m ( x – x) Formula Write the equation of the line that has a slope of 3 and passes through the point ( -3, 2). 1 st substitute into the formula. y – y = m ( x – x) y – 2 = 3 ( x – (-3)) y – 2 = 3 ( x + 3 ) y – 2 = 3x + 9 + 2 + 2 y = 3x + 11

Similar presentations

© 2023 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