How would combine 4x+5x?

Question

How do I combine these? It's a question I need to answer today in math class but I do not get it

Answer 1

since they have the same power of x you can just add the coefficients together!

4x + 5x = (4 + 5)x = 9x

Answer 2

Hi Stacy,

 

You can think of x as the number of things (say apples):

 

If I have 4 apples and 5 apples, how many apples do I have? (9 apples)

Likewise, you have 4x and 5x, so you have 9x altogether.

 

similarly, if I have 9 apples and you take away 4 apples from me, how many apples do I have? (5)

likewise 9x - 4x = 5x.

 

Let's look at 2 items now.

If I have 4 apples and 5 oranges, there is no way you can add them up different they are different items.

So 4x + 5y = 4x + 5y.

 

Hope this help you have a better understanding of algebra.

 

Answer 3

Hi Stacy;

4x is x+x+x+x

5x is x+x+x+x+x

9x is x+x+x+x+x+x+x+x+x