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PrecalculusSuperchallengeIntroduction to Limits

Introduction to Limits · Superchallenge problem

Express the area under y=3x2+1y=3x^{2}+1 over [0,2][0,2] as a right-endpoint Riemann sum with xk=2knx_{k}=\dfrac{2k}{n} and Δx=2n\Delta x=\dfrac{2}{n}, then evaluate

lim⁡n→∞∑k=1n(3xk2+1)Δx,\lim_{n\to\infty}\sum_{k=1}^{n}\Big(3x_{k}^{2}+1\Big)\Delta x,

using ∑k=1nk2=n(n+1)(2n+1)6\displaystyle\sum_{k=1}^{n}k^{2}=\frac{n(n+1)(2n+1)}{6}.