1. Warm-Up Exercises Divide each side by 2. Write original equation. Write 3x + 2y = 8 so that y is a function of x. EXAMPLE 2 Rewrite an equation Subtract 3x from each side. 3x + 2y = 8 2y2y = 8 – 3x 3 2 y=4 – x

2. Warm-Up Exercises GUIDED PRACTICE for Examples 2 and 3 3. Write 5x + 4y = 20 so that y is a function of x. 5 4 y=5 – x ANSWER

3. Warm-Up Exercises GUIDED PRACTICE for Examples 2 and 3 The perimeter P of a rectangle is given by the formula P = 2l + 2w where l is the length and w is the width. a. Solve the formula for the width w. 4. w = or w = – l P – 2l 2 ANSWER P 2

4. Warm-Up Exercises EXAMPLE 4 Solve a multi-step problem You are visiting Toronto, Canada, over the weekend. A website gives the forecast shown. Find the low temperatures for Saturday and Sunday in degrees Fahrenheit. Use the formula C = (F – 32) where C is the temperature in degrees Celsius and F is the temperature in degrees Fahrenheit. 5 9 Temperature

5. Warm-Up Exercises Simplify. Write original formula. EXAMPLE 4 Solve a multi-step problem Multiply each side by, the reciprocal of. 9 5 5 9 Add 32 to each side. SOLUTION STEP 1 Rewrite the formula. In the problem, degrees Celsius are given and degrees Fahrenheit need to be calculated. The calculations will be easier if the formula is written so that F is a function of C. (F – 32) 5 9 C= F – 32C 9 5 = 9 5 C + 32 = F · (F – 32) 9 5 5 9 C 9 5 =

6. Warm-Up Exercises EXAMPLE 4 Solve a multi-step problem ANSWER 9 5 = Therewritten formula is F C + 32.

7. Warm-Up Exercises Daily Homework Quiz 1. Write the equation 15 = 5y – 4x so that y is a function of x. y = x + 3 4 5 ANSWER 2. Solve C = 2  r for r. ANSWER r =  C 2 3. Solve V = Bh for B. 1 3 ANSWER B = 3V3V h

8. Warm-Up Exercises Extra Practice Solve for the given variable.