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Aug 27, 2020
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Thanks Loki and Heureka,

 

I went with a more straight forward (but not shorter) approach, 

I just divided by (x+1) three times to find the coefficients.

 

f(x)=ax5+bx4+cx3f(x)+2=ax5+bx4+cx3+2[f(x)+2]÷(x+1)=[ax5+bx4+cx3+2]÷(x+1)I did this by algebraic division and got a remainer of c+ba+2The remainder must be 0 soc+ba+2=0c=ba+2

 

So now I have

 

f(x)+2=ax5+bx4+(ba+2)x3+2[f(x)+2]÷(x+1)=[ax5+bx4+(ba+2)x3+2]÷(x+1)=ax4+(ba)x3+2x22x+2 (ax4+(ba)x3+2x22x+2)÷(x+1)I did this by algebraic division and got a remainder of 6b+2aThe remainder must be 0 so6b+2a=0b=6+2a (ax4+(ba)x3+2x22x+2)÷(x+1)=(ax4+(6+a)x3+2x22x+2)÷(x+1)=ax3+6x24x+2

 

(ax3+6x24x+2)÷(x+1)I did this by algebraic division and got a remainder of 12aThe remainder must be 0 soa=12 soa=12b=6+2a=30c=ba+2=3012+2=20sof(x)=12x5+30x4+20x3

 

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LaTex:

f(x)=ax^5+bx^4+cx^3\\
f(x)+2=ax^5+bx^4+cx^3+2\\
[f(x)+2]\div(x+1)=[ax^5+bx^4+cx^3+2]\div(x+1)\\
\text{I did this by algebraic division and got a remainer of }-c+b-a+2\\
\text{The remainder must be 0 so}\\
-c+b-a+2=0\\
c=b-a+2

 

f(x)+2=ax^5+bx^4+(b-a+2)x^3+2\\
[f(x)+2]\div(x+1)\\\qquad=[ax^5+bx^4+(b-a+2)x^3+2]\div(x+1)\\
\qquad =ax^4+(b-a)x^3+2x^2-2x+2\\~\\
(ax^4+(b-a)x^3+2x^2-2x+2)\div(x+1)\\
\\\text{I did this by algebraic division and got a remainder of }6-b+2a\\
\text{The remainder must be 0 so}\\
6-b+2a=0\\
b=6+2a\\~\\
(ax^4+(b-a)x^3+2x^2-2x+2)\div(x+1)\\
=(ax^4+(6+a)x^3+2x^2-2x+2)\div(x+1)\\
=ax^3+6x^2-4x+2

 

(ax^3+6x^2-4x+2)\div(x+1)\\
\\\text{I did this by algebraic division and got a remainder of }12-a\\
\text{The remainder must be 0 so}\\
a=12\\~\\
so\\
a=12\\
b=6+2a=30\\
c=b-a+2=30-12+2=20\\
so\\
f(x)=12x^5+30x^4+20x^3

Aug 27, 2020

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