Solving Two- Step Equations Lesson 4-4

Rules to Remember When solving an equation, the goal is to get the variable by itself. Addition and Subtraction are inverse operations. (opposites) Multiplication and Division are inverse operations. (opposites)

Don’t Forget The equation is like a balance scale. Whatever you do to one side of the equation must be done to the other side of the equation.

How to solve two-step equations “Undo” the operations in the reverse order of the order of operations. You are using the work back-words strategy In order of operations we do multiplication or division first, then addition and subtraction. When solving an equation we do the opposite!

Integer Rules to Remember Adding Integers Same sign= add and keep the sign Different sign = subtract and keep the sign of the larger number Subtracting Integers Keep, Change, Change Follow the rules for addition Multiplying and Dividing Integers Same Sign = Positive Answer Different Sign = Negative Answer

Let’s Try One… 3x + 2 = 23 - 2 -2 21 3x = 21 3 3 x = 7 - 2 -2 21 3x = 21 3 3 x = 7 The problem contains addition and multiplication. Which one do we undo 1st?

Another Example -2y – 7 = 3 +7 +7 10 -2y = 10 -2 -2 y = -5 +7 +7 10 -2y = 10 -2 -2 y = -5 The problem contains subtraction and multiplication. Which one do we undo 1st?

Last Example -3c + 9 = 3 -9 -9 -6 -3c = -6 -3 -3 c = 2 -9 -9 -6 -3c = -6 -3 -3 c = 2 The problem contains addition and multiplication. Which one do we undo 1st?

Now it’s your turn 5x + 4 = 19 2t + 7 = -1 6m + 1 = -23 -4w – 4 = 8