Solving Equations − Addition and Subtraction 1
Solving equations involves finding the value of an unknown variable. This is done by inversing − a process that reverses the equation. Let us take a look
The inverse of addition is subtraction and the inverse of subtraction is addition
Example 1. 6 + b = 14 What is the value of b?
Example 2. a − 12 = 5 What is the value of a?
Example 3. 50 + d = −30 What is the value of d?
The inverse of 6 is − 6. So subtract 6 from both sides
| 6 | + | b | = | 14 | ||
| − | 6 | = | − | 6 |
| b | = | 8 |
To verify, put the value of b = 8 back into the original equation
6 + 8 = 14
The inverse of − 12 is + 12. So add 12 to both sides
| a | − | 12 | = | 5 | ||
| + | 12 | = | + | 12 |
| a | = | 17 |
To check, put the value of a = 17 back into the original equation
17 − 12 = 5
The inverse of 50 is − 50. So subtract 50 from both sides
| 50 | + | d | = | −30 | |
| − | 50 | = | −50 |
| d | = | −80 |
To verify, put the value of d = −80 back into the original equation
50 + ( −80 ) = 50 − 80 = −30
Note: 'what is the value of y' is the same as 'solve y'
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