Bernoulli's inequality
In mathematics we mean by the Bernoulli's inequality, a simple but important inequality with which a power function can be estimated down.
For any real number, and any non-negative integer
Named the inequality after the Swiss mathematician Jacob Bernoulli.
- 4.1 exponential
- 4.2 Inequality of arithmetic and geometric means
Evidence
Bernoulli's inequality can be proved by mathematical induction. The induction base is met:
As induction hypothesis now applies to, and. Then it follows by the induction hypothesis and
After the induction principle the assertion holds for all.
Example
Assertion:
Real for all.
Proof: First, it is defined by
Then by Bernoulli's inequality
So
However, it is
Then so is
And ultimately
Related inequalities
Strict inequality
Also as Bernoulli's inequality the following inequality is called the " strictly greater ", " greater or equal " is used instead of one:
For all real numbers, and all natural numbers
The proof can also be by induction on the same pattern as the proof for the phrase " greater than" perform with.
Real exponents
For real exponents, the following generalizations can be demonstrated by comparison of the derivatives: For all
If and
When.
Variable factors
Considering not a power, but a product of different factors, so can be the following generalization by induction show:
If for all, or if for all and.
Substituting this and considered the special case, ie, we obtain the so-called Weierstrass product inequality
Applications
Exponential
Bernoulli's inequality is useful in many assessments. Fix a solid. Then for all. Therefore applies to the Bernoulli's inequality
Because of
Is thus the inequality
Proved.
Inequality of the arithmetic and geometric means
Using an estimate of the Bernoulli's inequality can the inequality of the arithmetic and geometric means prove inductively.
Sources and Notes
- Analysis
- Inequality