Cho \(f\left( x \right),g\left( x \right)\)  là hai hàm số liên tục trên R .

A. \(\int\limits_{}^{} {\left( {f\left( x \right).g\left( x \right)} \right)dx = \int\limits_a^b {f\left( x \right)dx.\int\limits_a^b {g\left( x \right)dx} } } \)

B. \(\int\limits_a^b {f\left( x \right)dx = 0} \)

C. \(\int\limits_a^b {f\left( x \right)dx = } \int\limits_a^b {f\left( y \right)dy} \)

D. \(\int\limits_a^b {\left( {f\left( x \right) - g\left( x \right)} \right)dx = \int\limits_a^b {f\left( x \right)dx - \int\limits_a^b {g\left( x \right)dx} } } \)