Need some help with adding and subtracting polynomials

Rafael De La Ghetto

New member
Joined
Jul 7, 2006
Messages
4
Hey guys can someone tell me how to do these? I have a whole page of them and if someone can tell me how to do 1 or the answer I will be able to figure it out.

#1 Add: (4x<sup>3</sup> - 2x<sup>2</sup> + x + 4) + (9 - x<sup>5</sup> - x<sup>2</sup> + 4x)

#2 Subtract: (x - 3x<sup>4</sup> + 2x<sup>2</sup>) - (-x<sup>3</sup> + 4x<sup>6</sup>)

Thanks guys
 

jonboy

Full Member
Joined
Jun 8, 2006
Messages
547
Re: Need some help

Rafael De La Ghetto said:
Hey guys can someone tell me how to do these? I have a whole page of them and if someone can tell me how to do 1 or the answer I will be able to figure it out.

#1 Add: (4x<sup>3</sup> - 2x<sup>2</sup> + x + 4) + (9 - x<sup>5</sup> - x<sup>2</sup> + 4x)

#2 Subtract: (x - 3x<sup>4</sup> + 2x<sup>2</sup>) - (-x<sup>3</sup> + 4x<sup>6</sup>)

Thanks guys
Ok when adding polynomial you always add "like terms". This means you can only add/subtract terms which have the same exponent. For example if you have 3x^5 and x^4 you cannot add this because of the different exponents 5 and 4. If you had 3x^4 and 2x^4 and you added them your answer would be 5x^4.


So for the first:


-2x^2 + -x^2 = -3x^2


x + 4x = 5x


4 + 9 = 13


So your answer is: -x^5 + 4x^3 - 3x^2 + 5x + 13


For the second (as you can see there is no like terms so we just re-write it in descending order, the greater is the one w/the highest exponent in the term):


-4x^6 - 3x^4 + x^3 + 2x^2 + x


or x(-4x^5 -3x^3 + x^2 + 2x + 1)

I say you have learned a lot in just those two problems alone. :)
 

tkhunny

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Apr 12, 2005
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9,778
Rafael De La Ghetto said:
Hey guys can someone tell me how to do these?
(4 dogs + 3 cats + 2 elephants) + (1 dog + 1 cat + 1 giraffe)

It helps me get a feel for what "like terms" means.
 

Denis

Senior Member
Joined
Feb 17, 2004
Messages
1,442
Rafael, did you know that "de la" is French for "of the"?
Just wondering if you're making a joke 8-)
 

Rafael De La Ghetto

New member
Joined
Jul 7, 2006
Messages
4
Re: Need some help

jonboy said:
Rafael De La Ghetto said:
Hey guys can someone tell me how to do these? I have a whole page of them and if someone can tell me how to do 1 or the answer I will be able to figure it out.

#1 Add: (4x<sup>3</sup> - 2x<sup>2</sup> + x + 4) + (9 - x<sup>5</sup> - x<sup>2</sup> + 4x)

#2 Subtract: (x - 3x<sup>4</sup> + 2x<sup>2</sup>) - (-x<sup>3</sup> + 4x<sup>6</sup>)

Thanks guys
Ok when adding polynomial you always add "like terms". This means you can only add/subtract terms which have the same exponent. For example if you have 3x^5 and x^4 you cannot add this because of the different exponents 5 and 4. If you had 3x^4 and 2x^4 and you added them your answer would be 5x^4.


So for the first:


-2x^2 + -x^2 = -3x^2


x + 4x = 5x


4 + 9 = 13


So your answer is: -x^5 + 4x^3 - 3x^2 + 5x + 13


For the second (as you can see there is no like terms so we just re-write it in descending order, the greater is the one w/the highest exponent in the term):


-4x^6 - 3x^4 + x^3 + 2x^2 + x


or x(-4x^5 -3x^3 + x^2 + 2x + 1)

I say you have learned a lot in just those two problems alone. :)
Thanks man, that was easy to understand.

Denis said:
Rafael, did you know that "de la" is French for "of the"?
Just wondering if you're making a joke 8-)
Yea its supposed to be a joke. I couldnt think of a username so I took a name from a Fresh Prince of Bell Air episode :p

Thanks again for all the help guys.
 
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