Docstoc

3 Slope intercept form

Document Sample
3 Slope intercept form Powered By Docstoc
					SWBAT… Write lines in slope-intercept form   1/7/09

Agenda
1. WU (5 min)
2. Notes on slope intercept

Warm Up
What is the slope of the line passing through (-5,
2) and (6, 7) in the standard (x, y) coordinate
plane?



     HW #2: Writing Equations in slope-intercept
Find the rate of change. Explain what
the rate of change means.

                                     Points Scored for 3-point Baskets

                        21
                        18
        Points Scored




                        15
                        12
                        9
                        6
                        3
                        0
                             0   1         2       3        4       5    6   7
                                                Number of Baskets
When an equation is in slope-intercept form:




   Now look at the equation below……

                    y  2x  1
           What is the slope? ____________



            What is the y-intercept? ____________
• y = mx+ b is an equation that defines a line
• A line has two characteristics
  – Points that fall on the line
  – Slope
  Converting linear
equations into Slope-
  Intercept Form
Slope intercept form is:

 y = mx + b
   Our main goal is to get
  the y alone on one side of
         the equation
Class example - convert Into Slope-Intercept Form

   2 y  4x  2
                      (divide both sides by 2 to get y alone)

           2 y  4x  2
           2        2
                                 (now simplify all fractions)
                      2              1
          2 y  4x  2
           2    2    2
             y  2x  1
    *** Your turn - example 1 ***
             Convert to Slope-Intercept Form:
 5y = 10x + 15
                       (divide both sides by 5 to get y alone)
 5 y  10 x  15
  5        5
                (now simplify all fractions)
5 y  10 x  15
5        5            5

         y = 2x + 3 BRAVO!!
*** Your turn – example 2 – convert                to
     Slope-Intercept Form ***

           -3y = -9x - 12

  Step 1: divide both sides by -3 to get y alone


  Step 2: Simplify all fractions


  Step 3: Write your equation in y = mx + b
         What is the slope? ____________


           What is the intercept? ____________
 *** Check Your Answer ***

-3y = -9x - 12        (divide both sides by -3 to get y alone)

 -3     -3
                       (now simplify all fractions)
-3y = -9x - 12
 -3    -3 -3
y = 3x + 4
      Slope = 3
                           Wow, you’re good
      Intercept = 4        at this!!
              ***Class example***
               Convert to Slope-Intercept Form:
  21x – 7y =14     (subtract both sides by 21x)
21x           -21x
                            (now divide both sides by -7)
   -7y = -21x + 14
   7 - 7 -7               (simplify all fractions)


    y = 3x – 2
***Final   Example - Your turn – example 3-Convert
           to Slope-Intercept Form          ***
              2y + 26 = -6x
     Step 1: Subtract both sides by 26

     Step 2: Divide both sides by 2 to get y by itself

     Step 3: Simplify all fractions

           What is the slope? ____________


            What is the intercept? ____________
*** Check Your Answer ***
2y + 26 = -6x     (subtract both sides by 26)
   26        -26
                    (now divide both sides by 2
2y = -6x - 26
 2 2 2
                      (simplify all fractions)

y = -3x - 13
            You are a math wizard!
Four students are renting a car for a road trip.
The cost of renting the car is given by the
function C = 12.5 + 21d, where C is the total
cost for renting the car for d days. What does
the slope of the function represent?
  1.   number of people
  2.   cost per day
  3.   number of days
  4.   miles per gallon
The cost of prints from an online photo
processor is given by C(p) = 29.99 +
0.13p. $29.99 is the cost of membership,
and p is the number of 4-inch by 6-inch
prints. What does the slope represent?
1.   cost per print
2.   cost of the membership
3.   cost of the membership and 1 print
4.   number of prints

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:17
posted:12/18/2011
language:English
pages:15