$30)\int\limits^1_0 {f(x)-2g(x)} \, dx=\int\limits^1_0 {f(x)} \, dx-2\int\limits^1_0 {g(x)} \, dx=2-2.5=-8\\ =>C\\ 31)\int\limits^2_1 \dfrac{dx}{3x-2}\\$$ =\dfrac{1}{3}\int\limits^2_1 \dfrac{d(3x-2)}{3x-2}\\ =\dfrac{1}{3}ln(|3x-2|) \Big|^2_1\\ =\dfrac{1}{3}ln4\\ =\dfrac{1}{3}ln(2^2)\\ =\dfrac{2}{3}ln2\\ =>A\\ 32)\int\limits^2_0 \dfrac{dx}{x+3}\\ =ln(|x+3|) \Big|^2_0\\ =ln5-ln3\\ =ln \dfrac{5}{3}\\ =>C$
