2-4 Writing Linear Equations Objective: To write an equation of a line in slope intercept form given the slope and one or two points, and to write an equation of a line that is parallel or perpendicular to the graph of a given equation.

Drill #22* Write the equation of the line (in point- slope form) passing through the following points and graph the line: 1.( 2, 5 ), ( 3, 8 ) 2.( -1, 3), ( 2, 4 ) 3.( 0, 1 ), ( 3, 1 )

Quiz tomorrow Writing equations in point- slope and slope- intercept forms given a point and the slope (parallel or perpendicular to another line) Graphing linear equations - know how to use slope and a point to graph - know how to use two points to graph Finding the line of best fit Using the line of best fit to make predictions

Classwork (#22*) 4.Find the equation of the line parallel to y = ¾ x + 2 and passing through ( -2, -4) and graph the line.

Find the value of k (#22*) Find the value of k in the following equations if the given ordered pair is a solution: 5.5x + ky = 8 (3, -1) 6.3x + 8y = k ( 0, ½ )

2-5 Scatter Plots Objective: To draw scatter plots and to find and use prediction equations.

Scatter Plot **(25.) Definition: The graph of related data points showing the correlation among the points. Generally a line of best fit can be drawn that approximates the relationship between the points. Using the equation of the line of best fit, we can predict values.

Plot the following data Note: When scaling axes find the maximum and minimum value for each variable. Make sure your axes are slightly bigger than your maximum values and slightly smaller than your minimum values

Scatter Plot: Weak Positive Correlation

Line of Best-Fit ** (26.) The Best-Fit line is the line that passes close to most of the data points. It does not have to pass through any of the data points. You can use the best-fit line to make predictions about the data.

Equation of the line of best-fit Find two points on the line: (7, 6) and (1, 0) Find the slope: m = 1 Substitute m and find b: y = 1x + b Substitute (1, 0) or (7, 6) 0 = 1(1) + b -1 = b y = 1x - 1

Prediction Equation **(27.) Definition: The prediction equation can be found using two points from the line of best fit (they do not have to be data points) The prediction equation can be used to estimate the value of one of the variables given the other.

Slope… What does the slope mean? What are the units? The slope means that the _____________ is y - unit _____________ by _____________ inc. / dec.slope every ______________ x - unit

Example 2 1.Make a scatter plot of the following data. 2.Draw a line of best fit. 3.Write an equation for the line of best fit relating the rate of pay (y) to the years of experience (x) Exp Rate$17$10 $7$6$12$20$15