Deriv

  • December 2019
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‫ﻣﻠﺨﺺ ﻟﻼﺷﺘﻘﺎق‬ ‫‪ -I‬اﻻﺷﺘﻘﺎق ﻓﻲ ﻧﻘﻄﺔ‪ -‬اﻟﺪاﻟﺔ اﻟﻤﺸﺘﻘﺔ‬ ‫‪ -1‬اﻻﺷﺘﻘﺎق ﻓﻲ ﻧﻘﻄﺔ‬ ‫أ‪ -‬ﺕﻌﺮﻳﻒ‬ ‫ﻟﺘﻜﻦ ‪ f‬داﻟﺔ ﻋﺪدﻳﺔ ﻣﻌﺮﻓﺔ ﻓﻲ ﻣﺠﺎل ﻣﻔﺘﻮح ﻣﺮآﺰﻩ ‪x0‬‬ ‫) ‪f(x ) − f(x 0‬‬ ‫ﻧﻘﻮل إن اﻟﺪاﻟﺔ ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻓﻲ ‪ x0‬اذا آﺎﻧﺖ ﻟﻠﺪاﻟﺔ‬ ‫‪x − x0‬‬

‫ﺑـ ) ‪ . f ' ( x0‬اﻟﻌﺪد ‪ l‬ﻳﺴﻤﻰ اﻟﻌﺪد اﻟﻤﺸﺘﻖ ل ‪ f‬ﻓﻲ ‪ . x0‬ﻧﻜﺘﺐ‬

‫→ ‪ x‬ﻧﻬﺎﻳﺔ ‪ l‬ﻓﻲ ‪ x0‬وﻧﺮﻣﺰ ﻟﻬﺎ‬

‫) ‪f ( x) − f ( x0‬‬ ‫‪x − x0‬‬

‫‪f ' ( x0 ) = lim‬‬ ‫‪x → x0‬‬

‫ب‪ -‬ﺥﺎﺻﻴﺔ‬ ‫آﻞ داﻟﺔ ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻓﻲ ‪ x0‬ﺕﻜﻮن ﻣﺘﺼﻠﺔ ﻓﻲ ‪x0‬‬

‫‪ – 2‬اﻻﺷﺘﻘﺎق ﻋﻠﻰ اﻟﻴﻤﻴﻦ ‪ -‬اﻻﺷﺘﻘﺎق ﻋﻠﻰ اﻟﻴﺴﺎر‬ ‫أ‪ -‬ﺕﻌﺮﻳﻒ‬ ‫*‬

‫ﻟﺘﻜﻦ ‪ f‬داﻟﺔ ﻣﻌﺮﻓﺔ ﻋﻠﻰ ﻣﺠﺎل ﻣﻦ ﺷﻜﻞ [‪ [ x0; x0 +α‬ﺣﻴﺚ ‪α ;0‬‬ ‫) ‪f(x ) − f(x 0‬‬ ‫ﻧﻘﻮل إن ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ اﻟﻴﻤﻴﻦ ﻓﻲ ‪ x0‬إذا آﺎﻧﺖ ﻟﻠﺪاﻟﺔ‬ ‫‪x − x0‬‬

‫→ ‪ x‬ﻧﻬﺎﻳﺔ ‪ l‬ﻋﻠﻰ اﻟﻴﻤﻴﻦ ﻓﻲ‬

‫‪ x0‬و ﻧﺮﻣﺰ ﻟﻬﺎ ﺑـ ) ‪. f d' ( x0‬‬ ‫اﻟﻌﺪد ‪ l‬ﻳﺴﻤﻰ اﻟﻌﺪد اﻟﻤﺸﺘﻖ ل ‪ f‬ﻋﻠﻰ اﻟﻴﻤﻴﻦ ﻓﻲ ‪x0‬‬

‫* ﻟﺘﻜﻦ ‪ f‬داﻟﺔ ﻣﻌﺮﻓﺔ ﻋﻠﻰ ﻣﺠﺎل ﻣﻦ ﺷﻜﻞ‬ ‫ﻧﻘﻮل إن ‪f‬‬

‫ﻧﻜﺘﺐ‬

‫) ‪f ( x) − f ( x0‬‬ ‫‪x − x0‬‬

‫‪x→x0‬‬

‫] ‪ ] xx − α ; x0‬ﺣﻴﺚ ‪α ;0‬‬

‫) ‪f(x ) − f(x0‬‬ ‫ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ اﻟﻴﺴﺎر ﻓﻲ ‪ x0‬إذا آﺎﻧﺖ ﻟﻠﺪاﻟﺔ‬ ‫‪x − x0‬‬

‫‪ x0‬ﻧﺮﻣﺰ ﻟﻬﺎ ب‬

‫‪f 'd ( x0 ) = lim+‬‬

‫→ ‪ x‬ﻧﻬﺎﻳﺔ ‪ l‬ﻋﻠﻰ اﻟﻴﺴﺎر ﻓﻲ‬

‫) ‪. f g' ( x0‬‬

‫اﻟﻌﺪد ‪ l‬ﻳﺴﻤﻰ اﻟﻌﺪد اﻟﻤﺸﺘﻖ ل ‪f‬‬

‫ﻋﻠﻰ اﻟﻴﺴﺎر ﻓﻲ ‪x0‬‬

‫ﻧﻜﺘﺐ‬

‫) ‪f ( x) − f ( x0‬‬ ‫‪x − x0‬‬

‫‪f 'g ( x0 ) = lim−‬‬ ‫‪x→x0‬‬

‫ب – ﺥﺎﺻﻴﺔ‬ ‫ﺕﻜﻮن ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻓﻲ ‪ x0‬إذا وﻓﻘﻂ إذا آﺎﻧﺖ ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ اﻟﻴﻤﻴﻦ وﻋﻠﻰ اﻟﻴﺴﺎر ﻓﻲ ‪x0‬‬

‫واﻟﻌﺪد اﻟﻤﺸﺘﻖ ﻋﻠﻰ اﻟﻴﻤﻴﻦ ﻳﺴﺎوي اﻟﻌﺪد اﻟﻤﺸﺘﻖ ﻋﻠﻰ اﻟﻴﺴﺎر‪.‬‬ ‫‪ -3‬اﻟﺘﺄوﻳﻞ اﻟﻬﻨﺪﺱﻲ – ﻣﻌﺎدﻟﺔ اﻟﻤﻤﺎس ﻟﻤﻨﺤﻨﻰ داﻟﺔ‬ ‫أ‪ -‬اﻟﻤﻤﺎس‬ ‫ﻟﺘﻜﻦ ‪ f‬داﻟﺔ ﻣﻌﺮﻓﺔ ﻋﻠﻰ ﻣﺠﺎل ﻣﻔﺘﻮح ﻣﺮآﺰﻩ ‪ x0‬و ‪ C f‬ﻣﻨﺤﻨﺎهﺎ‬ ‫ﻗﺎﺑﻠﻴﺔ اﺷﺘﻘﺎق ‪ f‬ﻓﻲ ‪ x0‬ﺕﺆول هﻨﺪﺱﻴﺎ‬

‫) ‪y = f ' ( x0 )( x − x0 ) + f ( x0‬‬

‫ﺑﻮﺝﻮد ﻣﻤﺎس ﻟـ ‪ C f‬ﻋﻨﺪ اﻟﻨﻘﻄﺔ ذات اﻷﻓﺼﻮل ‪ x0‬ﻣﻌﺎدﻟﺘﻪ‬

‫ب‪ -‬ﻧﺼﻒ اﻟﻤﻤﺎس‬ ‫إذا آﺎﻧﺖ ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ اﻟﻴﻤﻴﻦ ﻓﻲ ‪ ) x0‬أو ﻋﻠﻰ اﻟﻴﺴﺎر ﻓﻲ ‪ ( x0‬ﻓﺎن ‪ C f‬ﻳﻘﺒﻞ ﻧﺼﻒ ﻣﻤﺎس ﻋﻨﺪ اﻟﻨﻘﻄﺔ‬

‫ذات اﻻﻓﺼﻮل ‪ x0‬ﻣﻌﺎﻣﻠﻪ اﻟﻤﻮﺝﻪ )‪ ) fd' (x0‬أو)‪( fg' (x0‬‬ ‫‪ -4‬اﻟﺪ اﻟـــــﺔ اﻟﻤﺸﺘﻘﺔ‬ ‫أ‪ -‬ﺕﻌﺮﻳﻒ‬ ‫ﻧﻘﻮل إن ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ اﻟﻤﺠﺎل ‪ I‬إذا آﺎﻧﺖ ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻓﻲ آﻞ ﻧـﻘﻄﺔ ﻣﻦ ‪. I‬‬ ‫اﻟﺪاﻟﺔ اﻟﺘﻲ ﺕﺮﺑﻂ آﻞ ﻋﻨﺼﺮ ‪ x‬ﻣﻦ ‪ I‬ﺑﺎﻟﻌﺪد ) ‪ f ' ( x‬ﺕﺴﻤﻰ اﻟﺪاﻟﺔ اﻟﻤﺸﺘﻘﺔ ﻧﺮﻣﺰ ﻟﻬﺎ ﺑـ ' ‪. f‬‬ ‫ب‪ -‬ﻋﻤﻠﻴﺎت ﻋﻠﻰ اﻟﺪوال اﻟﻤﺸﺘﻘﺔ‬ ‫*‪ -‬ﻟﺘﻜﻦ ‪ f‬و ‪ g‬داﻟﺘﻴﻦ ﻗﺎﺑﻠﺘﻴﻦ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ ﻣﺠﺎل ‪ I‬و‬

‫\∈ ‪λ‬‬

‫‪(f‬‬

‫‪∀x ∈ I‬‬

‫) ‪+ g ) '( x ) = f '( x ) + g '( x‬‬

‫) ‪( f × g ) '( x ) = f '( x ) g ( x ) + f ( x) g '( x‬‬ ‫) ‪(λ f ) ' = λ f '( x‬‬ ‫)‪g '( x‬‬ ‫‪1‬‬ ‫=‬ ‫‪−‬‬ ‫‪x‬‬ ‫(‬ ‫)‬ ‫‪ ‬‬ ‫)‪g 2 ( x‬‬ ‫‪g‬‬ ‫'‬

‫)‪f '( x) g ( x) − f ( x) g '( x‬‬ ‫‪f‬‬ ‫= )‪  ( x‬‬ ‫)‪g2 ( x‬‬ ‫‪g‬‬ ‫'‬

‫‪ ∀x∈I‬ﺑﺤﻴﺚ ‪ g‬ﻻ ﺕﻨﻌﺪم ﻋﻠﻰ ‪I‬‬

‫*‪ -‬ﻟﺘﻜﻦ ‪ f‬داﻟﺔ ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ ﻣﺠﺎل ‪ I‬و }‪n ∈ `* − {1‬‬ ‫) ‪× f '( x‬‬

‫‪n −1‬‬

‫)) ‪( f ) ( x ) = n ( f ( x‬‬ ‫' ‪n‬‬

‫‪∀x ∈ I‬‬

‫*‬

‫‪ -‬ﻟﺘﻜﻦ ‪ f‬داﻟﺔ ﻗﺎﺑﻠﺔ ﻟﻼﺷﺘﻘﺎق ﻋﻠﻰ ﻣﺠﺎل ‪ I‬و ‪ n ∈] −‬و ‪ f‬ﻻ ﺕﻨﻌﺪم ﻋﻠﻰ ‪I‬‬

‫) ‪× f '( x‬‬

‫‪n −1‬‬

‫)) ‪( f ) ( x ) = n ( f ( x‬‬ ‫' ‪n‬‬

‫‪∀x ∈ I‬‬

‫ﺝﺪول ﻣﺸﺘﻘﺎت ﺑﻌﺾ اﻟﺪوال‬ Df '

f ' ( x)

f (x )

\

0

a

\

1

x

\*



1 x2

1 x

\

nx n −1

n ∈ `* − {1} x n

\*

nx n −1

\*+

1 2 x

n ∈ ]* −

xn x

\

− sin x

cos x

\

cos x

sin x

π  \ −  + kπ / k ∈ ]  2 

1 + tan 2 x

tan x

\

−a sin ( ax + b )

cos ( ax + b )

\

a cos ( ax + b )

sin ( ax + b )

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