dx/dt=[t*1/t-2t(1+lnt)/t^4=(-1-2lnt)/t³
dy/dt=[t*2/t-(3+2lnt)]/t²=(t-3-2lnt)/t²
dy/dx=(dy/dt)/(dx/dt)=(-1-2lnt)/(t²-3t-2tlnt)
d²y/dx²=d(dy/dx)/dx/dt
={[(-2/t)*(t²-3t-2tlnt)-(-1-2lnt)*(2t-3-2lnt-2)]/(t²-3t-2tlnt)²}÷(-1-2lnt)/t³
=t[-2t+6+4lnt+(1+2lnt)*(2t-5-2lnt)]/[(t-3-2lnt)²(-1-2lnt)]