Solving Equations by Adding or Subtracting Course 2

Solving Equations by Adding or Subtracting Course 2 2 -3

Addition Property of Equality

How to solve an equation Want to isolate variable (get it alone on one side of the equation) Can do this by using Inverse Operations

Inverse Operations undo each other Inverse Operations are Operations that Undo each other Addition and Subtraction are Inverse Operations Multiplication and Division are Inverse Operations

X – 34 = -46 Want to get x alone on 1 side of the equation What’s in the way of x being alone?

X – 34 = -46 34 is on the same side as x What’s 34 doing to X?

X – 34 = -46 34 is being subtracted from x. How do you undo subtraction?

X – 34 = -46 Addition undoes subtraction So ADD 34 to both sides of the equation X – 34 + 34 = -46 + 34

Now Simplify X – 34 + 34 = -46 + 34 X – 0 = -12 X = -12

Can Check Solution Put the solution back into the original equation and see if it is true X – 34 = -46 substitute -12 for x -12 – 34 -46 = -46 it is true, so solution is correct

Subtraction Property of Equality

Solve 114 + m = 249 Want to get m alone on 1 side of the equation What’s in the way of m being alone?

114 + m = 249 114 is in the way of m being alone. What is 114 doing to m?

114 + m = 249 114 is being added to m. How do you undo addition?

114 + m = 249 Subtraction undoes Addition. So SUBTRACT 114 from both sides of the equation. 114 + m – 114 = 249 - 114

Now simplify 114 + m – 114 = 249 - 114 – 114 + m = 135 0 + m = 135 Commutative Property of Addition

Check Solution Put the solution back into the original equation and see if it is true 114 + m = 249 substitute 135 for m 114 + 135 249 = 249 it is true, so solution is correct