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+ 0.74 + 0.67 + 0.61 + 0.55) = 0.81 .<br />

1<br />

∫<br />

0<br />

dx<br />

1 +<br />

1 (0.99 0.96 0.92 0.86 0.8<br />

2<br />

x ≈ 10<br />

+ + + + +<br />

+ 0.74 + 0.67 + 0.61 + 0.55 + 0.5) = 0.76 .<br />

1<br />

∫<br />

0<br />

dx<br />

1 +<br />

1 (0.75 0.99 0.96 0.92 0.86<br />

2<br />

x ≈ 10<br />

+ + + + +<br />

+ 0.8 + 0.67 + 0.61 + 0.55) = 0.782 .<br />

Òåïåð îá÷èñëèìî òî÷íî äàíèé ³íòåãðàë:<br />

1<br />

∫<br />

0<br />

dx<br />

1 + x<br />

2<br />

1<br />

π<br />

= arctgx<br />

0<br />

= ≈ 0.78539 .<br />

4<br />

Ïîð³âíÿííÿ íàáëèæåíèõ îá÷èñëåíü äàíîãî ³íòåãðàëà ç<br />

éîãî òî÷íèì çíà÷åííÿì äàþòü òàêèé ðåçóëüòàò: îòðèìàíà<br />

îäíà â³ðíà öèôðà çà ôîðìóëàìè ïðÿìîêóòíèê³â, à çà ôîðìóëîþ<br />

òðàïåö³¿ — äâ³ â³ðí³ öèôðè.<br />

Çàóâàæåííÿ 1. Î÷åâèäíî, ùî ç³ çá³ëüøåííÿì n òî÷í³ñòü<br />

ôîðìóë (9.10.1 – 9.10.3) ïîêðàùóºòüñÿ.<br />

Çàóâàæåííÿ 2. Êð³ì ôîðìóë (9.10.1 – 9.10.3), ³ñíóþòü<br />

é ³íø³, íàïðèêëàä ïàðàáîë³÷íà ôîðìóëà ѳìïñîíà 1 .<br />

1<br />

ѳìïñîí Òîìàñ (1710 – 1761) — àíãë³éñüêèé ìàòåìàòèê.<br />

ÒÅÌÀ 10<br />

ÔÓÍÊÖ²¯ ÁÀÃÀÒÜÎÕ Ç̲ÍÍÈÕ<br />

10.1. ÎÑÍÎÂͲ ÎÇÍÀ×ÅÍÍß ² ÏÎÍßÒÒß<br />

10.1.1. Ïðîáëåìí³ ïðèêëàäè<br />

Ïðè âèð³øåíí³ áàãàòüîõ ïèòàíü ãåîìåòð³¿, ïðèðîäîçíàâñòâà<br />

³, çîêðåìà, åêîíîì³êè ìàþòü ì³ñöå âèïàäêè, êîëè îäíà<br />

âåëè÷èíà çàëåæèòü â³ä äåê³ëüêîõ.<br />

Ïîÿñíèìî öå íà ïðèêëàäàõ.<br />

Ïðèêëàä 10.1.1. Ïëîùà S äîâ³ëüíîãî ïðÿìîêóòíèêà<br />

òàêà: S = xy. Ç ö³º¿ ôîðìóëè âèäíî, ùî âåëè÷èíà S çàëåæèòü<br />

â³ä äâîõ çì³ííèõ âåëè÷èí x ³ y (x — äîâæèíà, y —<br />

øèðèíà).<br />

Ïðèêëàä 10.1.2.  òåî𳿠åëåêòðèêè â³äîìèé çàêîí Îìà,<br />

ÿêèé ó â³äïîâ³äíèõ îäèíèöÿõ ïîâ’ÿçóº ñèëó ñòðóìó (I), íàïðóãó<br />

(U) ³ îï³ð (R). Öåé çàêîí ìîæíà îïèñàòè òàêîþ ôîðìóëîþ<br />

U<br />

I = .<br />

R<br />

Ïðèêëàä 10.1.3. Îá’ºì V äîâ³ëüíîãî ïðÿìîãî ïàðàëåëåï³ïåäà<br />

òàêèé: V = xyz. Öÿ ôîðìóëà ïîêàçóº, ùî âåëè÷èíà V<br />

áóäü-ÿêîãî ïðÿìîãî ïàðàëåëåï³ïåäà çàëåæèòü â³ä òðüîõ âåëè÷èí<br />

(x — äîâæèíà, y — øèðèíà, z — âèñîòà).<br />

Ïðèêëàä 10.1.4.  êëàñè÷í³é òåî𳿠åêîíîì³êè â³äîìî<br />

òàêå ñï³ââ³äíîøåííÿ<br />

MV = PY. (10.1.1)<br />

Âîíî íàçèâàºòüñÿ ð³âíÿííÿì îáì³íó Ô³øåðà, àáî îñíîâíèì<br />

ð³âíÿííÿì êëàñè÷íî¿ ê³ëüê³ñíî¿ òåî𳿠ãðîøåé.  öüîìó<br />

ð³âíÿíí³ áóêâîþ Ì ïîçíà÷åíî çàãàëüíó ê³ëüê³ñòü ãðîøåé;<br />

áóêâîþ V ïîçíà÷åíî øâèäê³ñòü ¿õ îáîðîòó (ñê³ëüêè ðàç<br />

êîæíà ãðèâíÿ, äîëàð ïðèéìຠó÷àñòü ó ðîçðàõóíêàõ ó ñåðåäíüîìó<br />

çà ð³ê); áóêâîþ Y ïîçíà÷åíî íàö³îíàëüíèé ïðîäóêò<br />

àáî äîõîä (íàö³îíàëüíèé ïðîäóêò, âèðàæåíèé âàðò³ñòþ, ñï³â-<br />

342 343

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