(2) (x)^n-((x'))^2+((x'))^3=0;-|||-(3) ^n+dfrac (2)(1-x)((x'))^2=0;-|||-(4) ^n+sqrt (1-{(x'))^2}=0;-|||-(5) (x)^n+([ 1+{(x'))^2] }^3/2=0 (常数 neq 0 );-|||-(6) ^n-dfrac (1)(t)(x)^t+((x'))^2=0 (提示:方程两端除以x`).