R-33 Consider the 2 points

 Consider these 2 points.

(2,6)
(0,4)

*What did I just give you?

The y-intercept because it's 0 as x and the number attached to it. 

Steps for Finding an equation from points

R-32 Steps for Finding an equation from points

 

L-32 Write a procedure to find an equation if you are given a point and a slope. Using a graph strategy? Using a table strategy? 

Homework: L-33 Due Tuesday

pg. 47 #6-8, pg.55 #57

Consider the points

Consider these three points.


(2,60) (3,75) (4,90)

Considering Perpendicular and Parallel lines

1. y= 3/4 +4
2. y=-4/3x+5
3. y=3/4x-2
4. y=-4/3x-3

Class Observations
*Lines 1 and 3 are parallel
*When lines intersect not on exact coordinates
*lines 2 and 4 are parallel 
*To get a perpendicular line you have to find the opposite reciprocal of the slope
1 and 3 are perpendicular to 2 and 4

What makes a perpendicular line?

R-30


y=3x+4


Is this perpendicular to


3y=2x-18 (or y=2x-9)
                           3
no, it is not perpendicular.

How do we put equations into normal format?

y +7=3x


How do you solve this if it is not in a normal format?


y+7=3x
  -7   -7


y=3x-7


y intercept=-7
slope=3      rise 3, run 1




L-28 Page


How do I find the y intercept in any equation? Even a funky equation.


Class Rule
 Find the y-intercept:
Put the equation into regular format (y=mx+b). The + or - b is the y-intercept. Remember, always do the same thing to both sides. Only y on the y-side.




Use that rule to solve this problem.


(y+4) = 2x
   6






y=12x+4


1. Parallel


y=12x+7
y=12x+2


*Slope stays the same, change y-intercept




2. Perpendicular


y=-12x+4
y=-1/12x +4
y=24x+4


*Clara and Boa think: Change the slope to it's opposite (positive then make it negative, negative then
make it positive)
*Max thinks: Turning it into a fraction


***Class is still not sure about perpendicular

Moving from an Equation to Graph and Table

R-28. Ms. O'toole gave you an equation to consider:

y=5x-4

Our noticings:

*+ slope because when I graphed it- no "N"
* y-intercept is -4 (y-intercept is where the line crosses the y axis, x=0
*Slope=5  in the equation   rise=5, run=1       5/1 (Rise of 5 and run of 1)
**You can get find any point on the line from the equation


y=-1/2x +3

Our Noticings:

*Slope is -1/2
*Rise is -1 and run is 2 or Slope is -1/2 and rise is 1 **The class is in disequilibrium of which one is correct.
* y-intercept is where the graph starts
*When I made the graph I got a neg. slope