Cho hai hàm số \(f \left( x \right);g \left( x \right) \) liên tục trên R. Trong các mệnh đề sau, mệnh đè nào sai?
A. \(\int\limits_{{}}^{{}}{\left[ f\left( x \right)-g\left( x \right) \right]dx}=\int\limits_{{}}^{{}}{f\left( x \right)dx}-\int\limits_{{}}^{{}}{g\left( x \right)dx}\)
B. \(\int\limits_{{}}^{{}}{kf\left( x \right)dx}=k\int\limits_{{}}^{{}}{f\left( x \right)dx}\,\,\left( k\in R \right)\)
C.\(\int\limits_{{}}^{{}}{\left[ f\left( x \right)+g\left( x \right) \right]}dx=\int\limits_{{}}^{{}}{f\left( x \right)dx}+\int\limits_{{}}^{{}}{g\left( x \right)dx}\)
D. \(\int\limits_{{}}^{{}}{f\left( x \right).g\left( x \right)}dx=\int\limits_{{}}^{{}}{f\left( x \right)dx}.\int\limits_{{}}^{{}}{g\left( x \right)dx}\)