an easy question (1 Viewer)

[blackfriday]

its easy, but not for me.

p.121 arnold ex 4.1 q.4(b)

im too stupid to work out how you divide p(x)=x^3-3x^2+4x-2 by (x+i). the example in the book on how to do it was crap.

thanks.

 

[withoutaface]

well (x+i)(x-i)=x²+1 so what we do is divide by x²+1 and then multiply by (x-i) and it should work out.

 

[nit]

how about just performing long division with x+i as your divisor, and P(x) as your dividend.

 

[Arkad]

well (x+i)(x-i)=x²+1 so what we do is divide by x²+1 and then multiply by (x-i) and it should work out.

I don't know about that, what happen if there are remainders? It'll take longer than just doing it the normal long division way with x+i as divident, because you got to divide the remainder by x+i after you've the done the long division with x²+1 as divident, I think.

Edit: yeah what nit said.

 

[Slidey]

its easy, but not for me.

p.121 arnold ex 4.1 q.4(b)

im too stupid to work out how you divide p(x)=x^3-3x^2+4x-2 by (x+i). the example in the book on how to do it was crap.

thanks.

P(x)=[x^2-(3+i)x+(3+3i)](x+i) + (1-3i)

Do it with synthetic division - much faster and much easier.

 

[withoutaface]

how about just performing long division with x+i as your divisor, and P(x) as your dividend.

I couldn't remember if you could divide by i in 4u maths
EDIT: On second thoughts it was a stupid thing to forget.

 

[blackfriday]

thanks guys but the answer hit me right after i made the post.