log x is at most x - 1
Builds on 1 + x is at most exp xLogarithm is the inverse of the exponential
Statement
For every real , with equality if and only if .
Remarks
Put into the inequality . Then .
The line is the tangent to the graph of at .
Replacing by gives . Mathlib states the main claim as Real.log_le_sub_one_of_pos.
Reading path
To understand this page from the ground up, read these 66 pages in order. The foundations come first.
- Convex function definition
- Limit point of a set definition
- Local maximum definition
- Sequence definition
- Strictly monotone function definition
- Slopes of a convex function are increasing statement
- Limit of a function definition
- Local minimum definition
- Real sequence definition
- Subsequence definition
- Continuity at a point definition
- Derivative definition
- One-sided limit definition
- Bounded sequence definition
- Geometric sequence definition
- Limit of a sequence definition
- Monotone sequence definition
- Series definition
- Continuous function definition
- Differentiable function definition
- Fermat's theorem on stationary points statement
- Sum of a finite geometric series statement
- Monotone convergence theorem for sequences statement
- Convergent sequence definition
- Every sequence has a monotone subsequence statement
- Squeeze theorem statement
- Cauchy product definition
- Partial sum definition
- Power series definition
- Intermediate value theorem statement
- Derivative function definition
- One-sided limits of a monotone function exist statement
- Bolzano–Weierstrass theorem statement
- The sequence r^n tends to zero for |r| < 1 example
- Radius of convergence definition
- Convergent series definition
- Higher derivative definition
- Boundedness theorem statement
- Continuity of the inverse of a strictly monotone continuous function statement
- A series of nonnegative terms converges iff its partial sums are bounded statement
- Absolute convergence definition
- Sum of a series definition
- Second derivative definition
- Extreme value theorem statement
- Comparison test statement
- Geometric series example
- Cauchy product of absolutely convergent series statement
- Rolle's theorem statement
- Ratio test statement
- Mean value theorem statement
- Ratio formula for the radius of convergence statement
- A differentiable function is convex iff its derivative is increasing statement
- A function with nonnegative derivative is increasing statement
- A function with positive derivative is strictly increasing statement
- The exponential series has infinite radius of convergence statement
- A function with nonnegative second derivative is convex statement
- Exponential function definition
- Exponential of a sum statement
- The exponential function is positive statement
- The exponential function is its own derivative statement
- The exponential function is convex statement
- The exponential function is strictly increasing statement
- 1 + x is at most exp x statement
- Natural logarithm definition
- Logarithm is the inverse of the exponential statement
- log x is at most x - 1 statement
Further reading
- Web https://en.wikipedia.org/wiki/Natural_logarithm, Definition and properties
About this page
| Tag | 04CBRA4JRK |
|---|---|
| URI | m2://04CBRA4JRK |
| Kind | statement, proposition |
| Writing | W0 stub |
| MSC | 33B10, 26D15 |
| Status | This copy of the site has no build data. Run m2 status 04CBRA4JRK. |
| Uses | 1 + x is at most exp x, Logarithm is the inverse of the exponential |
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