∫u^(1/2) du=(2/3)u^(3/2)+C下一步呢=(2/3)(sint)^(3/2) 【0到π/2】 -(2/3)(sint)^(3/2) 【π/2到π】=(2/3)[(sinπ/2)^(3/2)-(sin0)^(3/2)]-(2/3)[(sinπ)^(3/2)-(sinπ/2)^(3/2)]=(2/3)[1-0]-(2/3)[0-1]=2/3+2/3=4/3答案肯定是正的,正数函数积分的数值肯定是正的