y' = x' * √[(1-x)/(1+x)] + x * {√[(1-x)/(1+x)]}'= √[(1-x)/(1+x)] + x * √[(1+x)/(1-x)] * [(1-x)/(1+x)]'= √[(1-x)/(1+x)] + x * √[(1+x)/(1-x)] * [(1 - x + 1 + x) / (1 + x)²]= √[(1-x)/(1+x)] + 2x/ (1 + x)² * √[(1+x)/(1-x)]