Separation of Variables T (x,t)=X(xr(t) Substitution into eq X(s)_「0=-B2=-元 X(x)or(t) T'(t)=-oB2T(t) Then, I(t)=e-a() R X= X'(x)+B2X(x)=0 X(x)=Acos(Bx)+Bsin(Bx)Separation of Variables Substitution into eq '' ' 2 ( ) () ( ) () Xx t Xx t β λ αΓ = =− =− Γ ' 2 Γ =− Γ () () t t αβ Xx A x B x ( ) cos( ) sin( ) = + β β Then, p k C α ρ = ( ,) ( ) () T xt X x t n = Γ 2 ( ) ( ) t t e−αβ Γ = '' 2 X x Xx () () 0 + = β