Quick Start Expectations1. Fill in planner and HWRS

HW: p. 46, #5, 14, 16, 18, #39-42

2. Get a signature on HWRS

3. On desk: calculator, journal, HWRS, pencil, pen

4. Warm Up: next slide… back of HWRS

What tool can we use to solve for the slope?The slope algorithm!

(x1,y1) (x2, y2) y2 – y1

x2 – x1

(x1,y1) (x2, y2)

9 – 56 – 4

= 4/2 = 2m =

What tool can we use to solve for the y-intercept?A table!X Y

4 53 3

2 11 -1

0 -3

What is the equation?y = 2x + -3

Write an equation for the line with points (4, 5) and (6, 9)

As the number in the group increases by 1, the admission cost increases by $15.

Slope = 15 y-intercept = 60

y = 2.5x

Decide what the independent and dependent variables are.Find the unit rate (m, or slope).Look if the starting value (b) was given.If not work backwards to find when x = 0.

Find the slope (m)• Finding out the y-value change as x increases by 1.• Use the slope algorithm • Change in y divided by the change in x

Find the y-intercept (b)• Work backwards from the given points to point (0, b)

using slope• Use substitution with the slope and a given point (x, y)

Find the slope (m)• Find 2 points the line passes through• Use the slope algorithm

Find the y-intercept (b)• Work backwards from the given points to point (0, b)

using slope• Use substitution with the slope and a given point (x, y)

Dana’s work is correct. In general, if you know the slope of a line and a point on the line you can substitute these three values in for y, m, and x in the equation y = mx + b and solve the equation for b.

No, Chris has not used the coordinates of the two points correctly to find the slope. She put the differences in x on top! It should be the change in y divided by the change in x, for a slope of 2.The equation should be y = 2x – 3.