Cho f(x) là hàm số liên tục trên đoạn [a;b] và c thuộc

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

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

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

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