1+x⁴ (1+x⁴ )⁾(1-x⁴ )-(1-x⁴ )⁾(1+x⁴ ) 4x³(1-x⁴)-(-4x³)(1+x⁴)
y= ------------- = ---------------------------------------- = --------------------------------- =
1-x⁴ (1-x⁴ )² (1-x⁴ )²
4x³-4x⁷+4x³+4x⁷ 8x³
= -------------------------------- = -------------------
(1-x⁴ )² (1-x⁴ )²
y⁾=x² -lnx =2x -(1/x) =(2x²-1)/x