1. Chapter 3 – Solving Linear Equations 3.7 – Formulas and Functions

2. Today we will learn how to: Today we will learn how to: Solve a formula for one of its variables Solve a formula for one of its variables Rewrite an equation in function form Rewrite an equation in function form

3. 3.7 – Formulas and Functions So far, we have been working with equations that have one variable. So far, we have been working with equations that have one variable. Today, we are going to work with equations that have more than one variable. Today, we are going to work with equations that have more than one variable.

4. 3.7 – Formulas and Functions Formula – an algebraic equation that relates two or more real-life quantities Formula – an algebraic equation that relates two or more real-life quantities

5. 3.7 – Formulas and Functions Example 1 Example 1 Solve A = lw for w. Solve A = lw for w. Find the width of a rectangle that has an area of 42 ft. 2 and a length of 6 ft. Find the width of a rectangle that has an area of 42 ft. 2 and a length of 6 ft.

6. 3.7 – Formulas and Functions Example 2 Example 2 Solve for F. Solve for F.

7. 3.7 – Formulas and Functions Example 3 Example 3 Solve I = Prt for t. Solve I = Prt for t. Find the number of years t that $2800 was invested to earn $504 at 4.5% Find the number of years t that $2800 was invested to earn $504 at 4.5%

8. 3.7 – Formulas and Functions When you have an equation with x and y, you can re-write the equation two ways. When you have an equation with x and y, you can re-write the equation two ways. “y is a function of x” means you rearrange the equation so you have y = “y is a function of x” means you rearrange the equation so you have y = “x is a function of y” means you rearrange the equation so you have x = “x is a function of y” means you rearrange the equation so you have x =

9. 3.7 – Formulas and Functions Example 4 Example 4 Rewrite the equation 2x – y = 9 so that y is a function of x. Rewrite the equation 2x – y = 9 so that y is a function of x.

10. 3.7 – Formulas and Functions Example 5 Example 5 Write the equation 2x – y = 9 so that x is a function of y. Write the equation 2x – y = 9 so that x is a function of y. Use the result to find x when y = -2, -1, 0, and 1. Use the result to find x when y = -2, -1, 0, and 1.

11. 3.7 – Formulas and Functions HOMEWORK Page 177 #11 – 14, 16 – 34 even