Recipe
Integrate by parts with tabular integration
Use when: the same by-parts split has to be applied several times in a row, because one factor (usually a polynomial) needs repeated differentiation before it reaches 0
Goal: the finished antiderivative in one pass, without hand-tracking u, v, du, dv through several separate applications
Taught in Repeated parts and tabular integration · extends Integrate by parts
Quick recipe
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1
Put the polynomial factor (the one that would be u in ordinary by-parts) at the top of a D column, then repeatedly differentiate it, one row per derivative, until it reaches 0.
Example
For \int x^3e^{2x}\,dx: the D column is x^3,\ 3x^2,\ 6x,\ 6,\ 0.
Why: this is the same repeated u\to du\to d(du)\to\cdots chain that ordinary by-parts would produce one application at a time; the table just lays every round out at once.
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2
Put the other factor at the top of an I column, then repeatedly antidifferentiate it the same number of times as the D column has rows.
Example
For the same integral, dv=e^{2x}\,dx, so the I column is e^{2x},\ \tfrac12e^{2x},\ \tfrac14e^{2x},\ \tfrac18e^{2x}.
Why: each I-column entry is exactly the v that ordinary by-parts would compute at that round.
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3
Starting at +, multiply each D-row by the I-entry one row below it, alternating the sign every row, and stop once the D column hits 0.
Example
x^3\left(\tfrac12e^{2x}\right)-3x^2\left(\tfrac14e^{2x}\right)+6x\left(\tfrac18e^{2x}\right)-6\left(\tfrac1{16}e^{2x}\right)+C- the D column reaches exactly 0 after finitely many rows (a polynomial factor) — stop here; the table is complete.
- the D column never reaches 0 (like e^x paired with \sin x) — tabular integration in this simple form doesn't terminate; fall back to ordinary repeated by-parts and solve algebraically for the repeating integral instead.
Why: the alternating diagonal product is exactly the sum of boundary terms that repeated by-parts would have produced one round at a time, collected in a single pass.
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4
Combine like terms, then differentiate the result to confirm it reproduces the original integrand.
Example
\int x^3e^{2x}\,dx = \frac{x^3}{2}e^{2x}-\frac{3x^2}{4}e^{2x}+\frac{3x}{4}e^{2x}-\frac{3}{8}e^{2x}+CDifferentiating regenerates x^3e^{2x} after the other terms cancel in pairs.
Why: the same arithmetic-slip risk from ordinary by-parts is still present here, just spread across more rows.
Common mistakes
- Forgetting to alternate the sign, or starting the alternation at - instead of +.
- Stopping the table one row early, before the D column actually reaches 0.
- Swapping which factor goes in the D column, so the "wrong" factor is the one being repeatedly differentiated.
- Trying to force a table with no terminating row (like e^x\sin x) instead of recognizing that case needs the algebraic self-referential method instead.