1. Solving for a Variable In a Formula

2. Solving for a Variable in a Formula
Formulas are identical to equations except that there is more than one letter.
When you solve an equation, you isolate the variable.
When you solve a formula, they have to tell you which variable to isolate!

3. Solving for a Variable in a Formula
Let’s solve the equation 3x = 6
The 3 is connected to the x by multiplication.
To disconnect it we’ll have to un-multiply.
The opposite of multiply is divide, so we divide by 3.

4. Solving for a Variable in a Formula
Let’s solve the formula rt = d for t
The r is connected to the t by multiplication.
To disconnect it we’ll have to un-multiply.
The opposite of multiply is divide, so we divide by r.

5. Solving for a Variable in a Formula
Formulas are actually easier to solve than equations because you don’t have to actually do the arithmetic.
You can just rearrange the letters.

6. Solving for a Variable in a Formula
Let’s solve the formula for the perimeter of a triangle for side 1.
Perimeter = side1 + side 2 + side 3

7. Solving for a Variable in a Formula
Let’s solve the formula
p = s1 + s2 +s3 for s1
The other sides are connected to s1 by addition so we need to subtract.
Notice: The variable that you’re solving for can be on the right in your answer.

8. Solving for a Variable in a Formula
Let’s solve for h in the formula

9. Solving for a Variable in a Formula
You can’t cancel anything on the left because the V doesn’t cancel with the bottom.

10. Solving formulas It’s just like solving equations.
Peel the other variables away from the one you are isolating.
Reverse the order of operations:
Add or subtract first
Then multiply or divide
Only cancel if you can cancel completely.