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Question-197094




Question Number 197094 by MrGHK last updated on 07/Sep/23
Answered by sniper237 last updated on 07/Sep/23
⇒^(schwarz theo)  ∂_x ( t∂_t u+2u)=x^2   ⇒^(∫dx) t∂_t u+2u =(x^3 /3)+f(t)  ⇒^(homogen slt%)  u_H =(C/t^2 )  ⇒^(cte variat%)  ((C′(t))/t)=(x^3 /3)+f(t)    ⇒ C(t)= ((t^2 x^3 )/6)+∫tf(t)dt  ⇒^(gen slt%)   u(x,t)=(x^3 /6)+(1/t^2 )∫tf(t)dt
$$\overset{{schwarz}\:{theo}} {\Rightarrow}\:\partial_{{x}} \left(\:{t}\partial_{{t}} {u}+\mathrm{2}{u}\right)={x}^{\mathrm{2}} \\ $$$$\overset{\int{dx}} {\Rightarrow}{t}\partial_{{t}} {u}+\mathrm{2}{u}\:=\frac{{x}^{\mathrm{3}} }{\mathrm{3}}+{f}\left({t}\right) \\ $$$$\overset{{homogen}\:{slt\%}} {\Rightarrow}\:{u}_{{H}} =\frac{{C}}{{t}^{\mathrm{2}} } \\ $$$$\overset{{cte}\:{variat\%}} {\Rightarrow}\:\frac{{C}'\left({t}\right)}{{t}}=\frac{{x}^{\mathrm{3}} }{\mathrm{3}}+{f}\left({t}\right) \\ $$$$\:\:\Rightarrow\:{C}\left({t}\right)=\:\frac{{t}^{\mathrm{2}} {x}^{\mathrm{3}} }{\mathrm{6}}+\int{tf}\left({t}\right){dt} \\ $$$$\overset{{gen}\:{slt\%}} {\Rightarrow}\:\:{u}\left({x},{t}\right)=\frac{{x}^{\mathrm{3}} }{\mathrm{6}}+\frac{\mathrm{1}}{{t}^{\mathrm{2}} }\int{tf}\left({t}\right){dt} \\ $$
Commented by MrGHK last updated on 07/Sep/23
sir can you explain how you get U_H  sir
$${sir}\:{can}\:{you}\:{explain}\:{how}\:{you}\:{get}\:{U}_{{H}} \:{sir} \\ $$
Commented by sniper237 last updated on 08/Sep/23
ty′+2y=0⇒((y′)/y)=−(2/t)⇒ ln∣y∣=−2ln∣t∣+k
$${ty}'+\mathrm{2}{y}=\mathrm{0}\Rightarrow\frac{{y}'}{{y}}=−\frac{\mathrm{2}}{{t}}\Rightarrow\:{ln}\mid{y}\mid=−\mathrm{2}{ln}\mid{t}\mid+{k} \\ $$

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