Find $\displaystyle\int x^4\,dx$.
A$5x^5 + C$
B$\dfrac{x^5}{5} + C$
C$x^5 + C$
D$4x^3 + C$
Answer & Solution
Correct answer: B. $\dfrac{x^5}{5} + C$
Power rule for integration: $\displaystyle\int x^n\,dx = \dfrac{x^{n+1}}{n+1} + C$ for $n \neq -1$.
Plug $n = 4$: $\dfrac{x^5}{5} + C$.
Option A is the *derivative* of $x^4$, not the integral. Always check by differentiating your answer.
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