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Do Now 10/29/09

Do Now 10/29/09. Copy HW in your planner. Text page 239, #4-32 even

lesley-crawford
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Do Now 10/29/09

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  1. Do Now 10/29/09 • Copy HW in your planner. • Text page 239, #4-32 even • In your notebook, answer the following question. There are two skateboard ramps at a skate park. One ramp is 12 ft long and 6 ft tall. The other is 10 ft long and 8 ft tall. Which ramp do you think is steeper? How can you tell?

  2. Objective • SWBAT find the slope of a line and interpret slope as a rate of change

  3. Section 4.4 “Find Slope and Rate of Change” SLOPE- the ratio of the vertical change (the rise) to the horizontal change (the run) between any two points on a line. Slope = rise = change in y run change in x

  4. Slope Symbols The slope m of a line passing through two points and is the ratio of the rise change to the run. y run rise “positive slope” x

  5. Slope Symbols The slope m of a line passing through two points and is the ratio of the rise change to the run. y rise run x “negative slope”

  6. 6– 2 2– (– 4) 4 2 3 6 y2 –y1 m = x2 – x1 = = = Find a positive slope Find the slope of the line shown. Let (x1, y1) = (–4, 2) = (x2, y2) = (2, 6). Write formula for slope. Substitute. Simplify.

  7. y2 –y1 (– 1) – 2 m = = x2 – x1 4– 5 – 3 = 3 = –1 Find the slope of the line that passes through the points. (5, 2) and (4, –1) Let (x1,y1) = (5, 2) = (x2, y2) = (4, –1). Write formula for slope. Substitute. Simplify.

  8. – 6 –1– 5 3 = 6– 3 –2 = = y2 –y1 m = x2 – x1 XAMPLE 2 Find a negative slope Find the slope of the line shown. Let (x1,y1) = (3, 5) and (x2, y2) = (6, –1). Write formula for slope. Substitute. Simplify.

  9. – 4– 6 = 5– 0 10 – 2 = – = y2 –y1 5 m = x2 – x1 Find the slope of the line that passes through the points (0, 6) and (5, –4) Let (x1,y1) = (0, 6) and (x2, y2) = (5, –4). Write formula for slope. Substitute. Simplify.

  10. Find the slope of a horizontal and vertical line – 4 1– 5 4– 4 0 = = 3– 3 4– (– 2) 0 0 = = = y2 –y1 y2 –y1 6 m = m = x2 – x1 x2 – x1 Find the slope of the line shown. Let(x1, y1) = (– 2, 4) and (x2,y2) = (4, 4). Write formula for slope. Substitute. Simplify. EXAMPLE 4 Find the slope of the line shown. Let(x1,y1) = (3, 5)and(x2, y2) = (3, 1). Write formula for slope. Substitute. Division by zero is undefined.

  11. y2 –y1 m = x2 – x1 Identifying Slopes Positive slope Undefined Slope of 0 Negative slope

  12. Rate of Change A rate of change compares a change in one quantity to change in another quantity. Example: hourly wage A rate of change describes how pay increases with respect to time spent working.

  13. The table shows the cost of using a computer at an Internet cafe for a given amount of time. Find the rate of change in cost with respect to time. change in cost = change in time 3.5 = 14–7 = 4– 2 7 = 2 The rate of change in cost is $3.50 per hour. Rate of change

  14. The table shows the distance a person walks for exercise. Find the rate of change in distance with respect to time. change in distance = change in time 3– 1.5 = 0.05 = 60– 30 ANSWER The rate of change in distance is 0.05 mile/minute. Rate of change

  15. Section 4.4 “Slopes of Lines” How can you use algebra to describe the slope of a ramp? Complete the “Investigating Algebra Activity” on page 234 in your textbook. Complete the ‘Drawing Conclusions’ questions #1-6.

  16. y2 –y1 m = x2 – x1 What Did We Learn? • Slope • Rate of change A rate of change compares a change in one quantity to change in another quantity.

  17. Homework 24 • Text p. 239, #4-32 evens

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