Basic Math help

[RA]

I'm reviewing simplifying expressions. I get all right except this one, unless my answer key is wrong.
How does
p + 3s - (2p - 4s) = 7s-p ??

I get it to 7s + p - 2p what am I missing?

:)

[HarryChiling]

I'm reviewing simplifying expressions. I get all right except this one, unless my answer key is wrong.
How does
p + 3s - (2p - 4s) = 7s-p ??

I get it to 7s + p - 2p what am I missing?

:)

p + 3s - (2p - 4s) = 7s-p
p + 3s -2p + 4s = 7s - p
-p + 7s = 7s -p
7s - p = 7s - p

I don't get what the question or the problem is?

[RT]

7s + p - 2p can be further simplified to 7s + (p - 2p) which equals 7s -p

[RA]

Harry, it's just practice at simplifying expressions.



Thanks RT, but Sorry, I don't get what happens to the -2.
How does p -2p = -p

:)

[RT]

p is another way of saying 1p. So you have 1p - 2p (which is the same as saying 1p + -2p). In Algebra, when you have terms that have the same variable (p, in this case), you can just add up the numbers in front of the variable to simplify.

Let's say that "p" represented the number 4.
p = 4
-2p = -8

p - 2p = 4 -8 = -4

and... -4 = -p

This works for any number that you substitute for p.

[RA]

Thank you so much for clearing that up. I get it now.

:)

[HarryChiling]

Ok, I get it. It was just an exercise. Well you have the answer now, but like terms can alwasy be subtracted and addeds to one another.

p + 2p = 3p
p² + 2p² = 3p²
p³ + 2p³ = 3p³
p + 2p² = cannot be added together because the variable isn't alike.

This site is an awesome resource for math:
http://mathworld.wolfram.com/