Question

how to combine like terms

Answer 1

http://www.purplemath.com/modules/polydefs2.htm

Answer 2

Should help :) ^

Answer 3

Assuming you are talking about in an equation, to combine like terms, here is an example:

5x + 24y + 2x = 8y + 386 - 6x

First, you determine what terms you have: X and Y.
Next, we will start on one side of an equation and combine like terms:

5x + 24y + 2x = 8y + 386 - 6x
^ ^
5x and 2x have the same variable following the coefficient (the number before the variables X and Y) and since 5x is positive [seeing there is no negative sign in front of it] and 2x is positive [seeing that the sign in front of it is addition] so we add these two terms and you are left with the equation:

7x + 24y = 8y + 386 - 6x

Now we begin moving the like terms from the right side of the equation to the left:

7x + 24y = 8y + 386 - 6x
^ ^^ = ^^ ^
6x and -6x have the same variable (X), 24y and 8y have the variable (Y)
To move the variables from one side to the other, you must perform the same operation on both sides of the equation.
First, we will start with X:

7x + 24y = 8y + 386 - 6x
+6x = + 6x

We are moving the 6x on the RIGHT to the left side of the equation. We add 6x because it is negative on the right side and in order to "cancel out" a negative, we must do the opposite. -6x + 6x = 0, and we want to get rid of the -6x on the right and move it to the left. Since we added 6x to the right, we must do the same to the left, add 6x. And since 6x and 7x have the same variables of X, we can add 6x to 7x.
Next, lets do the same thing to Y:

13x + 24y = 8y + 386
-8y = -8y

We subtract 8y (because 8y is positive and to get rid of it, we subtract a negative 8y). 8y and 24y have the same variables of Y, so we can subtract 8y from 24y.

13x + 16y = 386


In short, here is what we did:

Add like terms on each sides of the equation: 5x + 24y + 2x = 8y + 386 - 6x
7x + 24y = 8y + 386 - 6x
Move like terms from the right to left: +6x -8y -8y +6x
Result: 13x + 24y = 386