1. Section 3.3 Using Formulas
Algebra Concepts
Section 3.3
Using Formulas

2. Formula- equation that shows a relationship between variables

3. Has anyone seen this formula. 𝑑=𝑟×𝑡 What do the variables represent

4. Joey is training for running a marathon. He can run 7 miles per hour
Joey is training for running a marathon. He can run 7 miles per hour. How far can he run in 3 hours?
Rate = 7 miles/hour
Time = 3 hours
What are you trying to find?

5. Write the formula.
Fill in the variables you know.
Find the missing variable.

6. The number of times a cricket chirps is based on the temperature.

7. The formula relating temperature is
𝐹= 𝑛 4 +37
𝑛 𝑖𝑠 𝑡ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑖𝑟𝑝𝑠 𝑖𝑛 𝑜𝑛𝑒 𝑚𝑖𝑛𝑢𝑡𝑒
𝑎𝑛𝑑 𝐹 𝑖𝑠 𝑡ℎ𝑒 𝑑𝑒𝑔𝑟𝑒𝑒𝑠 𝐹𝑎ℎ𝑟𝑒𝑛ℎ𝑒𝑖𝑡

8. Estimate the temperature if the cricket is making 94 chirps per minute.
Write the formula
Substitute the variable you know
Do the math!

9. 𝐹= 𝑛 4 +37 𝐹= 𝐹=
𝐹≈61°

10. Perimeter- is the distance around a figure
Perimeter for a rectangle is
𝑃=2𝑙+2𝑤
𝑙 𝑖𝑠 𝑡ℎ𝑒 𝑙𝑒𝑛𝑔𝑡ℎ 𝑎𝑛𝑑 𝑤 𝑖𝑠 𝑡ℎ𝑒 𝑤𝑖𝑑𝑡ℎ
𝑃 𝑖𝑠 𝑡ℎ𝑒 𝑝𝑒𝑟𝑖𝑚𝑒𝑡𝑒𝑟

11. Find the perimeter.
𝑃=2𝑙+2𝑤 𝑃=
𝑃=14+8
𝑃=22 𝑦𝑑𝑠. ALWAYS LABEL!!!!!

12. Area (of a plane figure)- is the inside shape or space measured in square units.

13. You could count up all the squaresOR
Use the formula 𝐴=𝑙𝑤

14. 𝐴=𝑙𝑤
𝐴=9 4 𝑠𝑞𝑢𝑎𝑟𝑒𝑠
𝑦𝑜𝑢 𝑎𝑙𝑠𝑜 𝑛𝑒𝑒𝑑 𝑡ℎ𝑒 𝑠𝑖𝑧𝑒 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑞𝑢𝑎𝑟𝑒𝑠
𝐴=36 𝑠𝑞. 𝑓𝑡. 𝑜𝑟 𝑓𝑡. 2

15. Now you can use any formula in Math!