Khi đó, 9 ∫ 0 g ( x ) d x bằng

3/22

Biết \(\int\limits_0^9 {f\left( x \right){\rm{d}}x} = 37\) và \[\int\limits_0^9 {\left[ {3f\left( x \right) - 2g\left( x \right)} \right]{\rm{d}}x} = 61\]. Khi đó, \(\int\limits_0^9 {g\left( x \right){\rm{d}}x} \) bằng

\( - 25\).

\(25\).

\( - 86\).

\(86\).

Giải thích

Ta có \[\int\limits_0^9 {\left[ {3f\left( x \right) - 2g\left( x \right)} \right]{\rm{d}}x} = 61 \Leftrightarrow 3\int\limits_0^9 {f\left( x \right){\rm{d}}x - } 2\int\limits_0^9 {g\left( x \right){\rm{d}}x} = 61\]

\[ \Leftrightarrow 111 - 2\int\limits_0^9 {g\left( x \right){\rm{d}}x} = 61 \Leftrightarrow \int\limits_0^9 {g\left( x \right){\rm{d}}x} = 25\]. Chọn B.