ALGEBRAALGEBRA

LESSON 3 – LESSON 3 –

SOLVING ONE-STEP SOLVING ONE-STEP ADDITION/SUBTRACTION ADDITION/SUBTRACTION EQUATIONSEQUATIONS

ONE-STEP EQUATIONSONE-STEP EQUATIONS

• An An equationequation is a statement that says is a statement that says two expressions are equaltwo expressions are equal

• To solve an equation containing a To solve an equation containing a variable means to find the value(s) of the variable means to find the value(s) of the variable that make(s) the equation true.variable that make(s) the equation true.

EXAMPLE: x = 4 is a solution to the EXAMPLE: x = 4 is a solution to the equation x + 6 = 10 because we all know equation x + 6 = 10 because we all know that 4 + 6 = 10that 4 + 6 = 10

x = 11 is not a solution because x = 11 is not a solution because 11 + 6 is not equal to 1011 + 6 is not equal to 10

SOLVING ONE-STEP SOLVING ONE-STEP EQUATIONSEQUATIONS

• A one-step equation is an equation A one-step equation is an equation that requires only one step to solve that requires only one step to solve itit

SOLVING EQUATIONS USING SOLVING EQUATIONS USING INVERSE OPERATIONSINVERSE OPERATIONS

• In order to solve any equation, we must In order to solve any equation, we must use inverse operationsuse inverse operations– the inverse of addition is subtractionthe inverse of addition is subtraction– the inverse of subtraction is additionthe inverse of subtraction is addition

Essentially, you are trying to make it so Essentially, you are trying to make it so the “x” is isolated.the “x” is isolated.

So, you are trying to make everything So, you are trying to make everything that is not attached to the “x” go that is not attached to the “x” go away (turn into zero)away (turn into zero)

SOLVING EQUATIONS USING SOLVING EQUATIONS USING INVERSE OPERATIONSINVERSE OPERATIONS

• If you see addition in an equation, you If you see addition in an equation, you will use subtraction to solve it.will use subtraction to solve it.

• Same goes for subtraction, but you use Same goes for subtraction, but you use addition.addition.

• REMEMBER: WHAT IS DONE TO ONE REMEMBER: WHAT IS DONE TO ONE SIDE OF AN EQUATION MUST ALSO BE SIDE OF AN EQUATION MUST ALSO BE DONE TO THE OTHER SIDEDONE TO THE OTHER SIDE

• ALWAYS CHECK YOUR ANSWER TO MAKE ALWAYS CHECK YOUR ANSWER TO MAKE SURE IT IS CORRECTSURE IT IS CORRECT

EXAMPLES OF EXAMPLES OF ADDITION/SUBTRACTION ADDITION/SUBTRACTION

EQUATIONSEQUATIONS

• x + 8 = 10x + 8 = 10

The 8 is not attached to the x. How The 8 is not attached to the x. How can I turn 8 into a zero? Show this! can I turn 8 into a zero? Show this! What you do to one side, you must What you do to one side, you must do to the other.do to the other.

x + 8 = 10x + 8 = 10 CHECK:CHECK:

- 8 -8- 8 -8 2 + 8 = 10?2 + 8 = 10?

x = 2x = 2 10 = 10 yes10 = 10 yes

EXAMPLES OF EXAMPLES OF ADDITION/SUBTRACTION ADDITION/SUBTRACTION

EQUATIONSEQUATIONS

• x – 9 = 11x – 9 = 11

Since the 9 is not attached to the x, Since the 9 is not attached to the x, make it go away. What would make it go away. What would make 9 (in this case – 9) into zero? make 9 (in this case – 9) into zero? Show this on both sides.Show this on both sides.

MORE EXAMPLESMORE EXAMPLES

ANY QUESTIONS??????ANY QUESTIONS??????

• HOMEWORK – Worksheet on HOMEWORK – Worksheet on Addition/Subtraction EquationsAddition/Subtraction Equations