Question

Need help, please explain, don't just give the answer ^_^




7y – x2 + 3x −17x – 5y + 2x2

A.
−13x2 + 1y

B.
x2 – 14x + 2y

C.
2x2 – 12xy

D.
3x2 + 20x + 12y

Answer 1

@jim_thompson5910

Answer 2

@pooja195

Answer 3

@zepdrix

Answer 4

\[\huge~\rm~\bf~7y – x^2 + 3x −17x – 5y + 2x^2 \]
combine like terms

Answer 5

\(\huge\rm\color{red}{(−x^2+2x^2)+(3x−17x)+(7y−5y)}\)

Answer 6

-1+2=?

Answer 7

Sorry Openstudy wasn't working. I have a question, does it matter which order you put them as?

Answer 8

Yes

Answer 9

^example

Answer 10

The like terms must be together so that they can be combined to simplfy the expression

Answer 11

Imagine you're a doctor working with an x-ray. You have a patient who needs 2 x-rays. You have another patient that needs 3 x-rays. In total, 2+3 = 5 x-rays are done.


If you wanted to make a shorthand note of the x-rays, you could use algebraic notation


For the first patient who needs 2 x-rays, you could write 2x
For the first patient who needs 3 x-rays, you could write 3x
Adding 2x to 3x gives you 2x+3x = 5x


This example shows how combining like terms works.


Now imagine we throw in some other variable y. Say y for yogurt. If we have 3x+10y we CANNOT add them because we can't say 3x+10y = 13x or 13y or 13xy. It makes no sense to say any of those three things. The two things are completely separate and can't be combined. So we just leave 3x+10y as it is

Anyways, that's just an example that hopefully helps. I'll let @pooja195 continue

Answer 12

Thanks Jim for explaining

Answer 13

But what I was asking was does it matter which order you put the group of like terms?

For example, instead of what you put, what if you did it in a different order? (with the like terms still together)

Answer 14

It does matter. You can put them in a different order but you need to move the sign with it.
Like
-x^2+2x^2 can also be written as 2x^2-x^2 and still has the same meaning
\[\huge~\rm~\bf~7y – x^2 + 3x −17x – 5y + 2x^2\]

Answer 15

Still not sure how to put them in order tho

Answer 16

Hint: Look at the signs

Answer 17

it doesn't matter because

x+y = y+x

in other words, you can add terms in any order

Answer 18

Wait then why can't it be 7y-5y?

Answer 19

You can write it like that

Answer 20

Meaning 7y-5y first

Answer 21

That's fine the order doesn't matter unless you have negatives then u just need to becareful to move the negative sign

Answer 22

7y-5y is fine

Answer 23

Ok so you can continue with the question

Answer 24

From here you just need to add/subtract..
\(\huge\rm\color{red}{(−x^2+2x^2)+(3x−17x)+(7y−5y)}\)
-1+2=?

Answer 25

1?

Answer 26

Great so now we have
From here you just need to add/subtract..
\(\huge\rm\color{red}{(x^2)+(3x−17x)+(7y−5y)}\)
3x-17x=?

Answer 27

-14?

Answer 28

Perfect! :)
\(\huge\rm\color{red}{(x^2)+(-14x)+(7y−5y)}\)
7y-5y=?

Answer 29

2y

Answer 30

Perfect! :)
\(\huge\rm\color{red}{(x^2)+(-14x)+(2y)}\)
Now remove the parentheses
+ sign goes away since it is -14
\(\huge\rm\color{red}{x^2-14x+2y}\)

Answer 31

Ok, thanks Pooja! (And Jim)

Answer 32

yw ^.^