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σ-algebras and measures
Which sets can be measured, and the countable additivity that makes limits work.
A σ-algebra is a family of sets closed under complements and countable unions; a measure assigns sizes additively over countable disjoint unions. Lebesgue measure gives intervals their length and extends to far stranger sets. Picture it: covering a set by intervals and taking the cheapest total length. Think it: not every set is measurable (Vitali), which is why the σ-algebra is part of the definition.
कार्यरत उदाहरण · integrate 1/10 dx from 2 to 5
चरणानुक्रमे
- \int_{2}^{5} \frac{1}{10}\, dx
First find an antiderivative F, then evaluate F(b) − F(a).
- \int \frac{1}{10}\, dx = \frac{x}{10}
The integral of a constant c is c·x.
- F(5) - F(2) = \left(\frac{1}{2}\right) - \left(\frac{1}{5}\right)
Fundamental theorem of calculus: plug in the limits.
- = \frac{3}{10}
Simplify.
उत्तर उघडा
आता तुम्ही प्रश्न निवडा, किंवा स्वतःचा प्रश्न टाइप करा किंवा रेखाटून दाखवा. प्रत्येक टप्प्यात, चित्रे आहेत, तुम्ही विचारण्याआधी उत्तर लपवलेले आहे.
मोफत खाते प्रत्येक शिकवणी वर टिपण्णी जोडते, तुम्ही पूर्ण केलेल्या गोष्टीचा नोंदवही, तुमच्या सोडविलेल्या समस्या एका ठिकाणी, आणि या पानाच्या विषयी तुम्ही विचारू शकता अशा शिक्षकाला. गणित स्वतःच सर्वांसाठी खुले आहे, दाखलन झालेले असो किंवा नसो.
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कसे कराल: σ-algebras and measures
- First find an antiderivative F, then evaluate F(b) − F(a).
- The integral of a constant c is c·x.
- Fundamental theorem of calculus: plug in the limits.
- Simplify.
लोक विचारतात ते प्रश्न
What is wrong with the Riemann integral?
It fails on functions that oscillate too much, and it does not interact well with limits: the limit of integrable functions need not be integrable. Lebesgue's integral fixes both.