Google
Câu hỏi: Cho hàm số $y=f\left( x \right),y=g\left( x \right)$ liên tục trên $\mathbb{R}$. Gọi S là diện tích phần gạch chéo trong hình vẽ. Mệnh đề nào dưới đây đúng?
A. $S=\int\limits_{-2}^{4}{\left| f\left( x \right)-g\left( x \right) \right|d\text{x}}$
B. $S=\int\limits_{-2}^{4}{\left[ f\left( x \right)-g\left( x \right) \right]d\text{x}}$
C. $S=\int\limits_{-2}^{1}{f\left( x \right)d\text{x}}+\int\limits_{1}^{4}{g\left( x \right)d\text{x}}$
D. $S=\int\limits_{-2}^{1}{f\left( x \right)d\text{x}}-\int\limits_{1}^{4}{g\left( x \right)d\text{x}}$
A. $S=\int\limits_{-2}^{4}{\left| f\left( x \right)-g\left( x \right) \right|d\text{x}}$
B. $S=\int\limits_{-2}^{4}{\left[ f\left( x \right)-g\left( x \right) \right]d\text{x}}$
C. $S=\int\limits_{-2}^{1}{f\left( x \right)d\text{x}}+\int\limits_{1}^{4}{g\left( x \right)d\text{x}}$
D. $S=\int\limits_{-2}^{1}{f\left( x \right)d\text{x}}-\int\limits_{1}^{4}{g\left( x \right)d\text{x}}$
Ta có $S=\int\limits_{-2}^{1}{\left| f\left( x \right) \right|d\text{x}}+\int\limits_{1}^{4}{\left| g\left( x \right) \right|d\text{x}}=\int\limits_{-2}^{1}{f\left( x \right)d\text{x}}+\int\limits_{1}^{4}{g\left( x \right)d\text{x}}$.
Đáp án C.