原式=∫x³dx/[x^4√(2x^8-2x^4+1)]=1/4∫d(x^4)/[x^4√(2(x^4-1/2)²+1/2)]=1/(4√2)∫d(x^4)/[x^4√((x^4-1/2)²+(1/2)²)]=1/(4√2)∫(1/2)sec²θdθ/[((1+tanθ)/2)*(secθ/2)] (设x^4-1/2...