# C3 polynomials and the remainder theoremWatch

Thread starter 7 years ago
#1
A questions asks me to devide by
by using the remainder theorem, while reading the solution I am told, (this is after they find D, the remainder), to substitute and
why did i have to make x = 0? The book dosnt explain this.

after solviing for D and substituting D value and x = 0
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7 years ago
#2
You put x=0 to get rid of the x's so can work it out easier

i.e. -7 = -3C + 29
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Thread starter 7 years ago
#3
(Original post by Nicknak256)
You put x=0 to get rid of the x's so can work it out easier

i.e. -7 = -3C + D
So i can just get rid of x? In which situations could i reuse this method?
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7 years ago
#4
how the hell is that C3?
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7 years ago
#5
(Original post by Core)
So i can just get rid of x? In which situations could i reuse this method?
Yeah, since 0X is basically 0, since anything multiplied by 0 is 0. I can't really think now where you would reuse this method but if you are given two equations which equal each other, like here (and also chapter 1 of C4 if you're doing that too etc), and you chose which values of x to substitute into it to find the unknowns, most of the time it's easier to substitute x=0
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7 years ago
#6
Could you not just use algebraic long division? http://en.wikipedia.org/wiki/Polynomial_long_division
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Thread starter 7 years ago
#7
(Original post by davidmarsh01)
Could you not just use algebraic long division? http://en.wikipedia.org/wiki/Polynomial_long_division
Unfortunately it specificaly asked me to use the remainder theorem just as i have been asked to use the trapezium rule in a test paper when i could have easily difrentiated, i suppose hey want us to no alternative methods that can be used in different situations.
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Thread starter 7 years ago
#8
(Original post by Nicknak256)
Yeah, since 0X is basically 0, since anything multiplied by 0 is 0. I can't really think now where you would reuse this method but if you are given two equations which equal each other, like here (and also chapter 1 of C4 if you're doing that too etc), and you chose which values of x to substitute into it to find the unknowns, most of the time it's easier to substitute x=0
I should have paid more attention to the question ty for your help.
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7 years ago
#9
(Original post by Core)
I should have paid more attention to the question ty for your help.
No problem
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