} x_{i}=a+i \Delta x \text { Use this definition of the intergral to evaluate } \int_{0}^{1} x^{3}+2 x^{2} d x \text {. } First of all, we have \int_{0}^{1} x^{3}+2 x^{2} d x=\lim _{n \rightarrow \infty} \sum_{i=1}^{n} Evaluating the sum gives \int_{0}^{1} x^{3}+2 x^{2} d x=\lim _{n \rightarrow \infty} Evaluating the limit gives \int_{0}^{1} x^{3}+2 x^{2} d x=
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