Cho các hàm số f(x) và g(x) liên tục trên R. Tìm mệnh đề sai

A. $\underset{a}{\overset{b}{\int }}f\left(x\right)\text{d}x=-\underset{b}{\overset{a}{\int }}f\left(x\right)\text{d}x$ 

B. $\underset{a}{\overset{b}{\int }}f\left(x\right).g\left(x\right)\text{d}x=\underset{a}{\overset{b}{\int }}f\left(x\right)\text{d}x.\underset{a}{\overset{b}{\int }}g\left(x\right)\text{d}x$ 

C. $\underset{a}{\overset{b}{\int }}\left[f\left(x\right)-g\left(x\right)\right]\text{d}x=\underset{a}{\overset{b}{\int }}f\left(x\right)\text{d}x-\underset{a}{\overset{b}{\int }}g\left(x\right)\text{d}x$ 

D. $\underset{a}{\overset{c}{\int }}f\left(x\right)\text{d}x+\underset{c}{\overset{b}{\int }}f\left(x\right)\text{d}x=\underset{a}{\overset{b}{\int }}f\left(x\right)\text{d}x$