 # to one side of an equation, When you do something.

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to one side of an equation, When you do something

you have to do exactly the same thing to the other side.

http://www.mathslideshows.com 1) Undo the addition or subtraction operation first, by using inverse operations. 2) Undo the multiplication or division operation second, by using inverse operations.

http://www.mathslideshows.com R emember The Party ?

Who’s the friend and who’s the boyfriend or girlfriend? 4 is the friend 3 is the boyfriend or girlfriend Undo add 4 by subtracting 4 Undo multiply 3 by dividing by 3 3x + 4 = 16

http://www.mathslideshows.com REMEMBER TO CROSS THINGS OUT SO YOU KNOW YOU ARE DOING IT RIGHT 3x + 4 = 16 -4 3x = 12 3 3 x = 4

http://www.mathslideshows.com 1) GOAL : Get the variable alone on one side of the equation. 2) You always perform the same operation to both sides of an equation. 3) To undo an operation you perform its opposite operation to both sides of the equation. 4) Undo addition or subtraction before you undo multiplication or division.

http://www.mathslideshows.com 2x + 4 = 10 Get the variable alone. - 4 - 4 Subtract 4 from both sides. 2x = 6 +4 and -4 cancel out __ __ 2 2 Divide both sides by 2 x = 3 2 divided by 2 cancel to 1

http://www.mathslideshows.com 3m - 10 = 17 + 10 +10 3m = 27__ __ 3 3 m = 9

http://www.mathslideshows.com – 4 = 8 Get the variable alone. 3 ( ) = 3 12 Multiply both sides by 3. x = 36 3 divided by 3 cancel to 1 x3x3 x3x3 +4 +4 Add 4 to both sides. x3x3 = 12 + 4 and -4 cancel out.

http://www.mathslideshows.com + 6 = 14 2 ( ) = 2 8 x = 16 x2x2 x2x2 - 6 - 6 x2x2 = 8 + 6 = 14 16 2 8 + 6 = 14 14 =

http://www.mathslideshows.com What Operation Do You Do? 1) 3x + 8 = 24 Subtract 8 2) 5x - 10 = 19 Divide by 3 FIRST SECOND Add 10 Divide by 5 3) x - 4 = 20 2 Add 4Multiply by 2 4) - 30 = -5x + 5 Subtract 5 Divide by -5

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Textbook: Page 123 Examples 8 - 19

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Think about what you need to do to isolate the variable. Get rid of addition or subtraction first. Second get rid of multiplication or division.

http://www.mathslideshows.com The End! Take out your study guide !

http://www.mathslideshows.com 1) Undo the addition or subtraction operation first, by using inverse operations. 2) Undo the multiplication or division second, by using inverse operations. #11

http://www.mathslideshows.com 2 Step Subtract/Multiply Equation 3m - 10 = 17 Get the variable alone. +10 +10 Add 10 to both sides. 3m = 27 +10 and -10 cancel out __ __ 3 3 Divide both sides by 3 m = 9 #12 Show your check. 3(9) – 10 =17 Finish your check. 27 – 10 =17 17 =17 3 divided by 3 cancel to 1

http://www.mathslideshows.com + 6 = 14 Get the variable alone. ( ) = 8 Multiply both sides by 2. x = 16 2 divided by 2 cancels out x2x2 x2x2 - 6 - 6 Subtract 6 from both sides. x2x2 = 8 #13 + 6 and -6 cancel out. + 6 = 14 16 2 8 + 6 = 14 14 = Show your check. Finish your check. 22

http://www.mathslideshows.com TEACHER NOTE : Use the following slides the next day when correcting homework.

http://www.mathslideshows.com HOMEWORK EXPLANATION

An Equation is like a balance scale. Everything must be equal on both sides. 20 2x +5 =

http://www.mathslideshows.com 20 2x +5 = What you do to one side of an equation, you must do to the other side to keep it balanced! -5

http://www.mathslideshows.com 15 2x = What you do to one side of an equation, you must do to the other side to keep it balanced! __ 2 __ 2

http://www.mathslideshows.com 7.5 x = What you do to one side of an equation, you must do to the other side to keep it balanced!

http://www.mathslideshows.com Try to solve this subtraction equation 18 n - 3 = How do you get n all by itself? +3

http://www.mathslideshows.com Try to solve this subtraction equation 21 n = How do you get n all by itself?

http://www.mathslideshows.com Show your check by substituting your answer back into the original equation. 18 n - 3 = 21

http://www.mathslideshows.com Try to solve this division equation x3x3 15 = How do you get x all by itself? 3 3

http://www.mathslideshows.com Try to solve this division equation x 45 = How do you get x all by itself?

http://www.mathslideshows.com SHOW YOUR CHECK! x3x3 15 = 45

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