f'(x) = 1/√(1-x²)f''(x) = [-1/(1-x²)] * [1/(2√(1-x²))] * (-2x) = x/(1-x²)^(3/2)f'''(x) = [(1-x²)^(3/2) - x * (3/2 (1-x²)^(1/2) * (-2x)]/(1-x²)³f(x)带Peano余项...