Cho \(\int\limits_0^5 {f\left( x \right)dx = 6} \) và \(\int\limits_0^5 {g\left( x \right)dx = 2} \). Hãy tính:
a) \(\int\limits_0^5 {\left[ {2f\left( x \right) + 3g\left( x \right)} \right]} dx\);
b) \(\int\limits_0^5 {\left[ {2f\left( x \right) - 3g\left( x \right)} \right]} dx\).