Integral of the reciprocal function

This gives the antiderivative of 1/x for x not equal to zero, which is the natural logarithm of the absolute value of x plus a constant. The absolute value makes the formula valid on both sides of zero, where separate constants of integration apply. It is also the basis for integrating 1/(ax+b) by substitution and for logarithmic terms in partial fraction decompositions with linear denominators.

\int \frac{1}{x}\,dx = \ln\left|x\right| + C

What the symbols mean

the variable of integration (nonzero real number)
constant of integration

About this formula

  • FieldMathematics
  • TopicIntegral calculus
  • LevelHigh school
  • Also calledintegral of 1/x, antiderivative of 1/x, natural logarithm integral, integral of one over x, log integral, integral of reciprocal

Write it in Obsidian

MathLive is a free visual math editor for Obsidian. Run Find a formula, type “integral of the reciprocal function”, and it goes into your note as editable LaTeX. You can also scan formulas from screenshots, PDFs and handwriting.

Related formulas