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Polynomial C2

Show that when 3x3 - 2x2 + 4 is divided by x - 1 the remainder is 5.


Could anyone tell me whether i add a 0x in the equation above?


Thank you!!
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Avatar for Robie96
Robie96
2
you have to add 0x1 and then do the Horner schema


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Original post by JamesNeedHelp2
Show that when 3x3 - 2x2 + 4 is divided by x - 1 the remainder is 5.


Could anyone tell me whether i add a 0x in the equation above?


Thank you!!


Depends what method you are using

If you are doing long division, yes

If you are using the remainder theorem, no
It doesn't matter if you add a 0x. It doesn't change or achieve anything. Use remainder theorem to find the remainder.
Original post by TenOfThem
Depends what method you are using

If you are doing long division, yes

If you are using the remainder theorem, no


aah right, im using the long division. Thanks again tenofthem. Havent forgot about the plus rep yet!! :smile:
Original post by morgan8002
It doesn't matter if you add a 0x. It doesn't change or achieve anything. Use remainder theorem to find the remainder.


thanks!
Original post by JamesNeedHelp2
aah right, im using the long division. Thanks again tenofthem. Havent forgot about the plus rep yet!! :smile:


Do you know the remainder theorem ... It would be easier for this question
Original post by TenOfThem
Do you know the remainder theorem ... It would be easier for this question


Im using the edexcel c2 book and havent been taught the remainder theorem yet. Having flicked through the book its in the upcoming pages. Thanks!
Original post by JamesNeedHelp2
Im using the edexcel c2 book and havent been taught the remainder theorem yet. Having flicked through the book its in the upcoming pages. Thanks!

Substitute x = 1 into the polynomial to get the remainder.
Original post by morgan8002
Substitute x = 1 into the polynomial to get the remainder.


Thank you, much easier!:smile:
Original post by JamesNeedHelp2
Im using the edexcel c2 book and havent been taught the remainder theorem yet. Having flicked through the book its in the upcoming pages. Thanks!


Ok

To be honest ... Practising the long division is a good exercise in logical thought and algebraic manipulation
Original post by TenOfThem
Ok

To be honest ... Practising the long division is a good exercise in logical thought and algebraic manipulation


I agree! I have been going through all the examples, and it helps to do each and every question, even if it seems repetitive. :cool:
Original post by JamesNeedHelp2
I agree! I have been going through all the examples, and it helps to do each and every question, even if it seems repetitive. :cool:


Hi James ... Your inbox is full so I cannot reply to your message
Original post by TenOfThem
Hi James ... Your inbox is full so I cannot reply to your message


Thanks for the info, i have deleted most messages, should be ok now!! :smile::smile:
Reply 14
Avatar for me2*
me2*
13
the main thing u need to know:
1. if i have a polynomial and if i sub x=5 and it equals zero then (x-5) is a factor and vice versa
"in general"
if f(X) is a polynomial and f(a)=0 then (x-a) is a factor


and..........
if we want to find the remainder when f(x) is divided by (x-a)
then sub x=a into the polynomial

1.if it equals zero (x-thatnumber) is a factor
Original post by me2*
the main thing u need to know:
1. if i have a polynomial and if i sub x=5 and it equals zero then (x-5) is a factor and vice versa
"in general"
if f(X) is a polynomial and f(a)=0 then (x-a) is a factor


and..........
if we want to find the remainder when f(x) is divided by (x-a)
then sub x=a into the polynomial

1.if it equals zero (x-thatnumber) is a factor


Thank you for the information.

I have this one polynomial where you have to show that when it is divided by a factor that it equals a number.

The question states "show that when 3x4 - 8x3 + 10x2 - 3x - 25 is divided by x + 1 the remainder is -1.

So am i not supposed to sub 1 into the equation to find the remainder of -1? But when i do, i does not equal to -1?

So surely, i must be doing something wrong?

Thank you!!
Original post by JamesNeedHelp2
Thank you for the information.

I have this one polynomial where you have to show that when it is divided by a factor that it equals a number.

The question states "show that when 3x4 - 8x3 + 10x2 - 3x - 25 is divided by x + 1 the remainder is -1.

So am i not supposed to sub 1 into the equation to find the remainder of -1? But when i do, i does not equal to -1?

So surely, i must be doing something wrong?

Thank you!!


Since you are dividing by (x+1) you need to substitute x=-1 into the function as that is the value needed to make the bracket =0
Original post by TenOfThem
Since you are dividing by (x+1) you need to substitute x=-1 into the function as that is the value needed to make the bracket =0


Appreciated once again :h:

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