✨ ベストアンサー ✨
部分分数分解
(2x³-1)/(x⁴+x)
=(2x³-1)/{x(x+1)(x²-x+1)}
=[(2x-1)/(x²-x+1)]+[1/(x+1)]-[1/x]
与式=∫[(2x-1)/(x²-x+1)]dx+∫[1/(x+1)]+∫[1/x]
●∫[f'(x)/f(x)]dx=log[f(x)]より
∫[(2x-1)/(x²-x+1)]dx=log[x²-x+1]
∫[1/(x+1)]=log[x+1]
∫[1/x]=log[x]
与式=log[x²-x+1]+log[x+1]-log[x]+C
=log[(x²-x+1)(x+1)/(x)]
=log[(x³+1)/(x)]
=log[x²+(1/x)]