W wkn0524 Mar 2010 26 0 Malaysia May 25, 2010 #1 Question is find all the roots : z^4 + 2z^3 + 5z^2 + 8z + 4 = 0 I"m stuck at the beginning of this question. But i knew how to do this type of question and only does not know how to start. Thanks.

Question is find all the roots : z^4 + 2z^3 + 5z^2 + 8z + 4 = 0 I"m stuck at the beginning of this question. But i knew how to do this type of question and only does not know how to start. Thanks.

earboth MHF Hall of Honor Jan 2006 5,854 2,553 Germany May 25, 2010 #2 wkn0524 said: Question is find all the roots : z^4 + 2z^3 + 5z^2 + 8z + 4 = 0 I"m stuck at the beginning of this question. But i knew how to do this type of question and only does not know how to start. Thanks. Click to expand... 1. By trial and error you can see that z = -1 is a root of the equation. (Actually z = -1 is a double root of the equation) Use long division to get the remaining terms. \(\displaystyle z^4 + 2z^3 + 5z^2 + 8z + 4 = 0~\implies~(z+1)^2 \cdot (z^2+4)=0\) 2. Go on!

wkn0524 said: Question is find all the roots : z^4 + 2z^3 + 5z^2 + 8z + 4 = 0 I"m stuck at the beginning of this question. But i knew how to do this type of question and only does not know how to start. Thanks. Click to expand... 1. By trial and error you can see that z = -1 is a root of the equation. (Actually z = -1 is a double root of the equation) Use long division to get the remaining terms. \(\displaystyle z^4 + 2z^3 + 5z^2 + 8z + 4 = 0~\implies~(z+1)^2 \cdot (z^2+4)=0\) 2. Go on!

W wkn0524 Mar 2010 26 0 Malaysia May 25, 2010 #4 I cant go on to next step... Before that i done this question z^4 + 2z^2 + 4 = 0 Let x = z^2 x^2 + 2x + 4 = 0 a = 1 , b = 2, c = 4 x = -b sqr b^2 -4ac / 2a then i can get the answers.

I cant go on to next step... Before that i done this question z^4 + 2z^2 + 4 = 0 Let x = z^2 x^2 + 2x + 4 = 0 a = 1 , b = 2, c = 4 x = -b sqr b^2 -4ac / 2a then i can get the answers.