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Question-186329




Question Number 186329 by ajfour last updated on 03/Feb/23
Answered by ajfour last updated on 03/Feb/23
Cubic curve: y=x^3 −x  Parabola:  x=h+(y−k)^2   x=h+(p−k)^2   p^3 −p=c  ⇒  p^2 =2kp+x−h−k^2   say    x−h−k^2 =t  p^2 =2kp+t  p+c=2kp^2 +tp  2kp^2 =(1−t)p+c=4k^2 p+2kt    ⇒  p=((c−2kt)/(4k^2 +t−1))   =((c−mt)/(m^2 +t−1))  now, since    p^2 =2kp+t  (c−mt)^2 =m(c−mt)(m^2 +t−1)                              +t(t+m^2 −1)^2   ⇒ c^2 +m^2 t^2 −2cmt  =cm^3 +cmt−cm−m^4 t−m^2 t^2 +m^2 t         +t^3 +2(m^2 −1)t^2 +(m^2 −1)^2 t  ⇒   t^3 −2t^2 +(3cm−m^2 +1)t  +c(m^3 −m−c)=0  ....
$${Cubic}\:{curve}:\:{y}={x}^{\mathrm{3}} −{x} \\ $$$${Parabola}:\:\:{x}={h}+\left({y}−{k}\right)^{\mathrm{2}} \\ $$$${x}={h}+\left({p}−{k}\right)^{\mathrm{2}} \\ $$$${p}^{\mathrm{3}} −{p}={c} \\ $$$$\Rightarrow\:\:{p}^{\mathrm{2}} =\mathrm{2}{kp}+{x}−{h}−{k}^{\mathrm{2}} \\ $$$${say}\:\:\:\:{x}−{h}−{k}^{\mathrm{2}} ={t} \\ $$$${p}^{\mathrm{2}} =\mathrm{2}{kp}+{t} \\ $$$${p}+{c}=\mathrm{2}{kp}^{\mathrm{2}} +{tp} \\ $$$$\mathrm{2}{kp}^{\mathrm{2}} =\left(\mathrm{1}−{t}\right){p}+{c}=\mathrm{4}{k}^{\mathrm{2}} {p}+\mathrm{2}{kt} \\ $$$$ \\ $$$$\Rightarrow\:\:{p}=\frac{{c}−\mathrm{2}{kt}}{\mathrm{4}{k}^{\mathrm{2}} +{t}−\mathrm{1}}\:\:\:=\frac{{c}−{mt}}{{m}^{\mathrm{2}} +{t}−\mathrm{1}} \\ $$$${now},\:{since}\:\:\:\:{p}^{\mathrm{2}} =\mathrm{2}{kp}+{t} \\ $$$$\left({c}−{mt}\right)^{\mathrm{2}} ={m}\left({c}−{mt}\right)\left({m}^{\mathrm{2}} +{t}−\mathrm{1}\right) \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:+{t}\left({t}+{m}^{\mathrm{2}} −\mathrm{1}\right)^{\mathrm{2}} \\ $$$$\Rightarrow\:{c}^{\mathrm{2}} +{m}^{\mathrm{2}} {t}^{\mathrm{2}} −\mathrm{2}{cmt} \\ $$$$={cm}^{\mathrm{3}} +{cmt}−{cm}−{m}^{\mathrm{4}} {t}−{m}^{\mathrm{2}} {t}^{\mathrm{2}} +{m}^{\mathrm{2}} {t} \\ $$$$\:\:\:\:\:\:\:+{t}^{\mathrm{3}} +\mathrm{2}\left({m}^{\mathrm{2}} −\mathrm{1}\right){t}^{\mathrm{2}} +\left({m}^{\mathrm{2}} −\mathrm{1}\right)^{\mathrm{2}} {t} \\ $$$$\Rightarrow\: \\ $$$${t}^{\mathrm{3}} −\mathrm{2}{t}^{\mathrm{2}} +\left(\mathrm{3}{cm}−{m}^{\mathrm{2}} +\mathrm{1}\right){t} \\ $$$$+{c}\left({m}^{\mathrm{3}} −{m}−{c}\right)=\mathrm{0} \\ $$$$…. \\ $$

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