244. Find $\int_{1}^{2}\left(5 x^{4}+2 \dot{x}-8\right) d x$.
Solution. $\int_{1}^{2}\left(5 x^{4}+2 x-8\right) d x=\int_{1}^{2} 5 x^{4} d x+\int_{1}^{2} 2 x d x-\int_{1}^{2} 8 d x=\left.x^{5}\right|_{1} ^{2}+$ $+x^{2}-\left.8 x\right|_{1} ^{2}=\left(2^{5}-1^{5}\right)+\left(2^{2}-1^{2}\right)-8(2-1)=26$.