Download Solving Equations by Adding and Subtracting

Solving Equations by Adding and
Subtracting
Think of an equation as a balance scale.
When you solve an equation, your goal is
to isolate the variable.
Golden Rule of Equations
What you do to one side of an equation, you
must do to the other side to keep it the
equation balanced.
ADDITION and SUBTRACTION
“balance” each other
MULTIPLICATION and DIVISION
“balance” each other
Addition Property of Equality
You can Add the same number to each side
of an equation without changing the value.
Y - 5 = 13
Y - 5 +(5) = 13 + 5
Y = 18
Subtraction Property of Equality
You can SUBTRACT the same number from
each side of an equation without changing
the value.
Y + 5 = 13
Y + 5 -(5) = 13 - 5
Y=8
Examples
1. t – 58 = 71
2. x – 6 = -55
3. 114 + m = 249
4. x – 34 = -46
Examples Cont.
5. x + x = 64
6. x – x = 64
7. The sale price of a camera is $119. This
is $35 less than the original price. What
was the original price?
Division Property of Equality
3x
= 18
1.
Examples
5b = -235
2.
-7h = 35
3.
d/4 = 7
Remember: Whatever you do to one side
of an equation, you must do to the other!
Be careful: you cannot
divide by zero:
Division by ZERO is
UNDEFINED