∫[[1/(√x-1)]dx=∫[2√x/(√x-1)]d(√x)=∫[(2√x-2+2)/(√x-1)]d(√x)=∫[2 +2/(√x-1)]d(√x)=2√x+2ln|√x-1| +C选B
letu=√xdu = dx/(2√x)dx = 2u du∫ dx/(√x -1)=∫ 2u/(u-1) du=∫ [2 + 2/(u-1)] du=2u +2ln|u-1| +C=2√x + 2|√x-1| +Cans : B