1. Transforming Formulas Chapter 4.4

2. What is a formula? A formula shows a relationship between two or more variables. To transform a formula, you rewrite it to describe one quantity in terms of the others.

3. Formula: d = rt d = distance, r = rate, t = time Suppose we want to calculate the rate, not distance. Solve for rate (r). d = rt If t and d were just normal numbers, we would do the inverse: divide both sides by t to get r by itself. This is the answer: a rearranged formula. No numbers!

4. Sam drives 180 miles in three hours. If his rate is constant, how fast did he drive? What do we want to know? –RATE What should we know already? d = rt (distance = (rate)(time) How fast did he go? 180 = r(3) 3r =1803 r = 60 mph We divide the distance by time.

5. Treat the variables like numbers, use inverse operations. Solve each equation for the given variable: ab + 10 = 3; a ab + 10 = 3 –10 ab = –7 We want a by itself.

6. a = bcd – e; Solve for c a + e = bcd – e+eInverse a + e = bcd We are multiplying c by two variables. We can divide them both in one step.

7. Homework: pg 177 (1-8 all, 10-13 all)