How to integrate by parts

Today you will finally find this out

Humans have been wondering if it was possible to talk with noo-human creatures for centuries

Here is how to calculate \int x \cdot e^x \, dx:

  • Step 1: Apply the integration by parts method:
\int u \, dv = u\,v - \int v \, du
  • Step 2: Choose u and dv:

    • u = x \;\Rightarrow\; du = dx
    • dv = e^x \, dx \;\Rightarrow\; v = e^x
  • Step 3: Substitute into the formula:

\int x \, e^x \, dx = x \, e^x - \int e^x \, dx
  • Step 4: Solve the remaining integral:
\int e^x \, dx = e^x + C
  • Step 5: Combine the results:
\int x \, e^x \, dx = x \, e^x - e^x + C = e^x (x - 1) + C

Result #

\boxed{\int x \, e^x \, dx = e^x (x - 1) + C}

Check #

Differentiating the result confirms it:

\frac{d}{dx}\left[e^x (x - 1)\right] = e^x (x - 1) + e^x \cdot 1 = x \, e^x \quad \checkmark

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