1. Do Now 1. If f(x) = │(x² – 50)│, what is the value of f(-5) ?
A B C. 0 D E. -75
2. ( √2 - √3 )² =
A √6 B. 5 - √6 C √6 D. 1 - √2 E. 1 =
A B C D E. 226

2. P.3 Lines in the Plane SWBAT 1. Find the slope of a line.
2. Write linear equations given points on lines and their slopes.
3. Use slope-intercept forms of linear equations to graph lines.
4. Use slope to identify parallel and perpendicular lines.

3. The slope of a line
Slope: rise over run, the change in y over the change in x

4. The slope of a line Finding slope given 2 points:
1. (-2, 0) and (3, 1)
2. (-1, 2) and (2, 2)
3. (3, 4) and (3, 1)

5. The point-slope form of a line
Point-slope form: y – y1 = m(x – x1)
Find an equation of the line that passes through the point (1, -2) and has a slope of 3.
Find an equation of the line that passes through (2, - 3) and (4, 5).

6. Using point-slope to create linear models
During 1997, Barnes and Noble’s net sales were $2.8 billion, and in 1998 net sales were $3.0 billion.
1. Write a linear equation giving the net sales y in terms of the year x.
2. Use the equation to estimate the net sales during

7. Linear extrapolation: an approximation in which the estimated point lies outside of the given points
Linear interpolation: the estimated point lies between the two given points

8. Sketching graphs of lines
Slope-intercept form: y = mx + b
Better suited to graph linear equations

9. Sketching graphs of lines
Determine the slope and y-intercept of each linear equation and describe its graph.
1. x + y = 2
2. y = 2

10. Parallel Lines Parallel lines: have slopes that are equal
Find the slope-intercept form of the equation of the line that passes through the point (2, -1) and is parallel to the line 2x – 3y = 5.

11. Perpendicular Lines
Perpendicular lines: have slopes that are negative reciprocals
Find an equation of the line that passes through the point (2, -1) and is perpendicular to the line x – 3y = 5.