ok im taking physics now,and my math is kind of rusty,when combining like terms with numbers ........?

lol good luck with physics. I'm in gr.12 physics.. everyone says to drop it. But nope!

Ex.

2a + 4a +7b +9ab

The like terms are 2a and 4a because they have the same variable (letter).

So = 6a + 7b + 9ab

Ex. 2

2a + 3a^2 - 4b^2 + 6b^3 - b^2

If the variable has an exponent attached to it, they must have the same exponent (little top number) to be like.

So 4b^2 and b^2 are like.

Even though 2a and 3a^2 both have an "a", the exponent isn't the same = not like.

:)