Solving Equations

1
Solving Equations

• Adding/Subtracting

2
An equation is like a balance. Both sides must
be equal.

10
5 5
3
You must keep the equation balanced

• If you add or subtract a number on one side of an
  equation, you must do the same to the other side.
  
• 4 4
• So, 4 12 4 12
• If a b
• a - 7 b - 7

4
Inverse Operations

• Adding and Subtracting are opposites!
• They are called inverse operations because they
  undo each other.

5
Solve Equations by Subtracting

• Solve for x
• x 4 5
• We want to get x by itself.
• What is the opposite of adding 4?
• Subtracting 4!
• x 4 - 4 5 - 4
• x 1

6
Solve Equations by Subtracting

• Solve for g
• 7 g 10
• We want to get g by itself.
• What is the opposite of adding 7?
• We will subtract 7 from both sides of the
  equation!
• 7 - 7 g 10 - 7
• g 3

7
Solve Equations by Subtracting

• Solve for m
• 3 m 5
• We want to get m by itself.
• What is the opposite of adding 5?
• We will subtract 5 from both sides of the
  equation!
• 3 - 5 m 5 - 5
• -2 m

8
Try These!

• x 5 11
• 6 y 14
• 8 n 8
• Answers
• x 6
• y 8
• n 0

9
Solve Equations by Adding

• Solve for x
• x - 4 -1
• What is the opposite of subtracting 4?
• Adding 4!
• x - 4 4 -1 4
• x 3

10
Solve Equations by Adding

• Solve for a
• a - 5 9
• What is the opposite of subtracting 5?
• We will add 5 to both sides!
• a - 5 5 9 5
• a 14

11
Solve Equations by Adding

• Solve for n
• -2 n 8
• This is the same as
• n (-2) 8
• n - 2 8
• What is the opposite of subtracting 2?
• We will add 2 to both sides of the equation!
• n - 2 2 8 2
• n 10

12
Try These!

• Solve
• p - 3 8
• 5 c - 10
• -4 f 8
• Answers
• p 11
• c 15
• f 12