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Question Number 49151 by rahul 19 last updated on 03/Dec/18

Let z is complex number satisfying  the equation z^2 −(3+i)z+m+2i=0,  where mεR. Suppose the equation  has a real root, then find the non real root?

$${Let}\:{z}\:{is}\:{complex}\:{number}\:{satisfying} \\ $$$${the}\:{equation}\:{z}^{\mathrm{2}} −\left(\mathrm{3}+{i}\right){z}+{m}+\mathrm{2}{i}=\mathrm{0}, \\ $$$${where}\:{m}\epsilon{R}.\:{Suppose}\:{the}\:{equation} \\ $$$${has}\:{a}\:{real}\:{root},\:{then}\:{find}\:{the}\:{non}\:{real}\:{root}? \\ $$

Answered by mr W last updated on 03/Dec/18

z_1 =a=the real root  z_2 =p+qi=the non real root  a+p+qi=3+i  a(p+qi)=m+2i  q=1  a+p=3  aq=2⇒a=2  ap=m  ⇒p=1  ⇒z_2 =1+i  m=2

$${z}_{\mathrm{1}} ={a}={the}\:{real}\:{root} \\ $$$${z}_{\mathrm{2}} ={p}+{qi}={the}\:{non}\:{real}\:{root} \\ $$$${a}+{p}+{qi}=\mathrm{3}+{i} \\ $$$${a}\left({p}+{qi}\right)={m}+\mathrm{2}{i} \\ $$$${q}=\mathrm{1} \\ $$$${a}+{p}=\mathrm{3} \\ $$$${aq}=\mathrm{2}\Rightarrow{a}=\mathrm{2} \\ $$$${ap}={m} \\ $$$$\Rightarrow{p}=\mathrm{1} \\ $$$$\Rightarrow{z}_{\mathrm{2}} =\mathrm{1}+{i} \\ $$$${m}=\mathrm{2} \\ $$

Commented by rahul 19 last updated on 04/Dec/18

thanks sir ����

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