Section 8.3 Slope and y-intercept Algebra Concepts Section 8.3 Slope and y-intercept

When you go skiing, what does slope refer to?

Slope= 𝑣𝑒𝑟𝑡𝑖𝑐𝑎𝑙 𝑐ℎ𝑎𝑛𝑔𝑒 ℎ𝑜𝑟𝑖𝑧𝑜𝑛𝑡𝑎𝑙 𝑐ℎ𝑎𝑛𝑔𝑒

Slope-ratio that describes the tilt of a line

Positive slope= 𝑟𝑖𝑠𝑒 𝑟𝑢𝑛 Rise 1st Run 2nd

Negative slope= 𝑓𝑎𝑙𝑙 𝑐𝑟𝑎𝑤𝑙 Fall 1st Crawl 2nd

http://www. youtube. com/watch http://www.youtube.com/watch?annotation_id=annotation_2728764519&feature=iv&src_vid=ZzU8x5cMR-w&v=ZcSrJPiQvHQ

Find slope of a line Pick two points on the line Start at the left most point Count spaces to rise (+) or fall (-) Count spaces to run or crawl (always positive)

slope= 𝑟𝑖𝑠𝑒 𝑟𝑢𝑛 = 5 3

slope= 𝑓𝑎𝑙𝑙 𝑐𝑟𝑎𝑤𝑙 = −11 6

Finding the slope of a line using two points on the line 𝑠𝑙𝑜𝑝𝑒= ∆𝑦 ∆𝑥 3−(−1) 4−(−2) 4 6 = 2 3

Find the slope of the line containing these two points #1 5,−2 𝑎𝑛𝑑 2,1 #2 7,8 𝑎𝑛𝑑 (4,10)

Real life slopes A unit cost can be written as a slope $2 per pound has a slope of 2 35 miles per hour has a slope of 35

Assignment #50A Worksheet

Y-intercept-point where a line crosses the y-axis

http://www.youtube.com/watch?v=_YCwGdiUnKE

Graphing a line

Find the slope and y-intercept #1 𝑦= 4 5 𝑥−3 #2 𝑦=− 1 3 𝑥+5 #3 𝑦=6𝑥+2 #4 𝑦=𝑥−3 #5 𝑦=− 5 2 𝑥

To graph Plot the y-intercept From that point, use the slope to move to a new point Plot the second point Draw the line Add arrows 𝑦= 3 5 𝑥−2

If a line is not in slope intercept form, solve the equation for y using algebra. #1 3𝑥+4𝑦=20 #2 2𝑦+𝑥=8

Slope intercept rap http://www.youtube.com/watch?v=REjcPZeypVg

Assignment #50B Pg. 402 #2,4-9,11-19 odd 45,46