Mrs.Volynskaya
A formula is a type of literal equation. A literal equation is an equation with two or more variables.
To solve for one of the variables, use inverse operations.

Step 1 Locate the variable you are asked to solve for in the equation.
Step 2 Identify the operations on this variable and the order in which they are applied.
Step 3 Use inverse operations to undo operations and isolate the variable.

1.
2.
3.
4.
Add 4y to both sides
Simplify
Divide both sides by 2
Does it simplify?
2 x - 4y = 7
+ 4y + 4y
2 x = 7 + 4y
2 2
7

4 x

2 y
This fraction cannot be simplified because both terms in the numerator are not divisible by 2.

1.
2.
3.
4.
Answer Now

2x - 4 y = 7
1.
Subtract 2x from both sides
2.
Simplify
3.
Divide both sides by -4
4.
Does it simplify?
-2x - 2x
Nope!
-4 y = 7 - 2x
-4 -4 y

7


4
2 x

4) Solve for y: 4x – 2 y = 12
1.
Subtract 4x from both sides
2.
Simplify
3.
Divide both sides by -2
4.
Does it simplify?
4x – 2 y = 12
- 4x - 4x
-2 y = 12 – 4x
-2 -2 y = -6 + 2x or y = 2x - 6
Yes!

1.
2.
3.
4.
-4x + 12
4x - 12
-2x + 6
2x - 6
Answer Now

1. Solve for x 2. Solve for y

Lesson Quiz: Part I
Solve for the indicated variable.
1. for h
2. P = R – C for C
C = R – P
3. 2x + 7y = 14 for y
4. for m m = x ( k – 6)
5.
for C
C = Rt + S

Lesson Quiz: Part II
Euler’s formula, V – E + F = 2, relates the number of vertices V, the number of edges E, and the number of faces F of a polyhedron.
6. Solve Euler’s formula for F.
F = 2 – V + E
7. How many faces does a polyhedron with 8 vertices and 12 edges have?
6