$$ \int_1^2 x^4 dx = \left. \frac{x^5}{5} \right|_1^2 $$ $$ \int_1^2 x^4 dx == \frac{2^5}{5} - \frac{1^5}{5}$$ $$ \int_1^2 x^4 dx == \frac{32}{5} - \frac{1}{5}$$ $$ \int_1^2 x^4 dx == \frac{31}{5} = 6 \frac{1}{5}$$