a=√(1-x)x=1-a²dx=-2adax=3/4,a=1/2x=1,a=0所以原式=∫(1/2,0)-2ada/(a-1)2a/(a-1)=(2a-2+2)/(a-1)=2+2/(a-1)所以原式=-[2a+2ln|a-1|](1/2,0)=-[(0+0)-(1-2ln2)=1-2ln2