Juin 2003 Solution

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‫اﻣﺘﺤﺎن ﻳﻮﻧﻴﻮ‪2003‬‬

‫اﻟﺤـــﻞ‬ ‫اﻟﺘﻤﺮﻳﻦ‪1‬‬ ‫‪2‬‬

‫‪ -1‬ﻧﺤﺴﺐ ﺑﺎﺳﺘﻌﻤﺎل اﻟﻤﻜﺎﻣﻠﺔ ﺑﺎﻷﺟﺰاء ‪I = ∫ ln ( x ) dx‬‬ ‫‪1‬‬

‫‪2‬‬ ‫‪1‬‬ ‫‪2‬‬ ‫‪2‬‬ ‫‪2‬‬ ‫‪dx = [ x ln x ]1 − ∫ dx = [ x ln x ]1 − [ x ]1 = 2ln 2 − 1‬‬ ‫‪1‬‬ ‫‪x‬‬

‫‪ -2‬أﺡﺴﺐ اﻟﺘﻜﺎﻣﻞ ‪x e x dx‬‬

‫‪ln 4‬‬

‫‪∫0‬‬

‫‪2‬‬

‫‪2‬‬

‫× ‪I = ∫ ln ( x ) dx = [ x ln x ]1 − ∫ x‬‬ ‫‪2‬‬

‫‪1‬‬

‫‪1‬‬

‫) ﻳﻤﻜﻦ وﺿﻊ ‪( t = e x‬‬

‫ﻟﻴﻜﻦ ]‪x ∈ [ 0;ln 4‬‬ ‫ﻧﻀﻊ‬

‫‪2‬‬ ‫‪dx 2‬‬ ‫أي ‪dx = dt‬‬ ‫‪ t = e x‬وﻣﻨﻪ ‪ x = 2ln t‬و ﺑﺎﻟﺘﺎﻟﻲ =‬ ‫‪t‬‬ ‫‪dt t‬‬

‫‪t = 1‬‬ ‫‪ x =0‬‬ ‫‪⇔‬‬ ‫‪‬‬ ‫‪t = 2‬‬ ‫‪x = ln 4‬‬ ‫‪2‬‬ ‫‪2‬‬ ‫‪2‬‬ ‫إذن ‪x e x dx = ∫ ( 2ln t ) × t × dt = 4∫ ln (t ) dt = 4I = 8ln 2 − 4‬‬ ‫‪1‬‬ ‫‪1‬‬ ‫‪t‬‬

‫‪ln 4‬‬

‫‪∫0‬‬

‫اﻟﺘﻤﺮﻳﻦ‪2‬‬ ‫ﻟﻴﻜﻦ ‪ Ω‬آﻮن اﻹﻣﻜﺎﻧﻴﺎت‬

‫‪ -1‬ﻧﺤﺴﺐ ) ‪ p ( A‬و ) ‪p ( B‬‬ ‫ﻟﺪﻳﻨﺎ ‪ " : A‬ﻟﻠﻜﺮﺕﻴﻦ اﻟﻤﺴﺤﻮﺑﺘﻴﻦ ﻧﻔﺲ اﻟﻠﻮن"‬

‫‪cardA C 62 + C 22 15 + 1 16 4‬‬ ‫= ) ‪p (A‬‬ ‫=‬ ‫=‬ ‫=‬ ‫=‬ ‫‪card Ω‬‬ ‫‪28‬‬ ‫‪28 7‬‬ ‫‪C 82‬‬ ‫ﻟﺪﻳﻨﺎ ‪ " : B‬ﺟﺪاء اﻟﻌﺪدﻳﻦ اﻟﻤﺴﺠﻠﻴﻦ ﻋﻠﻰ اﻟﻜﺮﺕﻴﻦ اﻟﻤﺴﺤﻮﺑﺘﻴﻦ ﻣﻨﻌﺪم "‬

‫‪cardB C 42 + C 41 × C 41 6 + 16 22 11‬‬ ‫= ) ‪p (B‬‬ ‫=‬ ‫=‬ ‫=‬ ‫=‬ ‫‪card Ω‬‬ ‫‪28‬‬ ‫‪28 14‬‬ ‫‪C 82‬‬ ‫‪ -2‬ﻧﺤﺪد ﻗﺎﻧﻮن اﺡﺘﻤﺎل اﻟﻤﺘﻐﻴﺮ اﻟﻌﺸﻮاﺋﻲ ‪.X‬‬

‫}‪X ( Ω ) = {0;1; 2;3‬‬ ‫‪6‬‬ ‫‪3‬‬ ‫=‬ ‫‪28 14‬‬

‫‪12 3‬‬ ‫=‬ ‫‪28 7‬‬ ‫‪4+3 1‬‬ ‫=‬ ‫‪28‬‬ ‫‪4‬‬

‫=‬

‫=‬

‫‪C 42‬‬

‫=‬

‫‪C 82‬‬

‫‪C 41 × C 31‬‬ ‫‪C 82‬‬

‫‪C 41 × C 11 + C 32‬‬ ‫‪C 82‬‬ ‫‪3‬‬ ‫‪28‬‬

‫=‬

‫=‬

‫=‬

‫‪C 31 × C 11‬‬ ‫‪C 82‬‬

‫) ‪card ( X = 0‬‬

‫=‬

‫‪card Ω‬‬

‫)‪card ( X = 1‬‬ ‫‪card Ω‬‬

‫) ‪card ( X = 2‬‬ ‫‪card Ω‬‬

‫=‬

‫= )‪p ( X = 0‬‬

‫= )‪p ( X = 2‬‬

‫)‪card ( X = 3‬‬ ‫‪card Ω‬‬

‫= )‪p ( X = 1‬‬

‫= )‪p ( X = 3‬‬

‫ﻗﺎﻧﻮن اﺡﺘﻤﺎل ‪X‬‬ ‫‪3‬‬

‫‪2‬‬

‫‪1‬‬

‫‪0‬‬

‫‪3‬‬ ‫‪28‬‬

‫‪1‬‬ ‫‪4‬‬

‫‪3‬‬ ‫‪7‬‬

‫‪3‬‬ ‫‪14‬‬

‫‪xi‬‬

‫)‬

‫‪p (X = x i‬‬

‫اﻟﺘﻤﺮﻳﻦ‪3‬‬

‫ﻧﻌﺘﺒﺮ اﻟﻤﻌﺎدﻟﺔ ‪mz 2 − 2z + m = 0‬‬

‫‪1+ i‬‬ ‫‪ -1‬ﻧﺒﻴﻦ أن ﺡﻠﻲ اﻟﻤﻌﺎدﻟﺔ ) ‪ ( E‬هﻤﺎ‬ ‫‪m‬‬

‫∈‪z‬‬ ‫=' ‪z‬‬

‫‪(E ) :‬‬ ‫‪1− i‬‬ ‫و‬ ‫‪m‬‬

‫اﻟﻤﻤﻴﺰ اﻟﻤﺨﺘﺼﺮ ﻟﻠﻤﻌﺎدﻟﺔ ) ‪ ( E‬هﻮ ‪= 1 − 2 = −1 = i 2‬‬ ‫وﻣﻨﻪ‬

‫‪1+ i‬‬ ‫‪m‬‬

‫=' ‪z‬‬

‫‪1− i‬‬ ‫و‬ ‫‪m‬‬

‫'‪z‬‬ ‫‪ -2‬ﻧﻜﺘﺐ آﻞ ﻣﻦ ' ‪ z‬و " ‪ z‬و‬ ‫"‪z‬‬

‫‪2‬‬

‫=" ‪z‬‬

‫‪ d = 1 − m ⋅ m = 1 − m‬ﻷن ‪m = 2‬‬

‫=" ‪z‬‬

‫ﻋﻞ اﻟﺸﻜﻞ اﻟﻤﺘﻠﺜﻲ‪.‬‬

‫‪π‬‬ ‫‪‬‬ ‫;‪2‬‬ ‫‪1 + i ‬‬ ‫‪4   π‬‬ ‫‪‬‬ ‫=' ‪ z‬و‬ ‫=‬ ‫‪= 1; − α ‬‬ ‫‪m‬‬ ‫‪ 2;α   4‬‬ ‫‪‬‬ ‫‪‬‬ ‫‪‬‬

‫‪π‬‬ ‫‪‬‬ ‫;‪2‬‬ ‫‪−‬‬ ‫‪1 − i ‬‬ ‫‪4   π‬‬ ‫‪‬‬ ‫=" ‪z‬‬ ‫=‬ ‫‪= 1; − − α ‬‬ ‫‪m‬‬ ‫‪4‬‬ ‫‪ 2;α ‬‬ ‫‪‬‬ ‫‪‬‬ ‫‪‬‬ ‫‪‬‬

‫‪ π‬‬ ‫‪‬‬ ‫‪1; − α ‬‬ ‫‪‬‬ ‫'‪z‬‬ ‫‪4‬‬ ‫‪ = 1; π ‬‬ ‫‪= ‬‬ ‫‪z"  π‬‬ ‫‪  2 ‬‬ ‫‪α‬‬ ‫;‪1‬‬ ‫‪−‬‬ ‫‪−‬‬ ‫‪‬‬ ‫‪‬‬ ‫‪4‬‬ ‫‪ -3‬ﻧﺒﻴﻦ أن اﻟﺮﺑﺎﻋﻲ ‪ OABC‬ﻣﺮﺑﻊ ‪.‬‬ ‫' ‪ z‬و " ‪ z‬و " ‪ z '+ z‬أﻟﺤﺎق اﻟﻨﻘﻂ ‪ A‬و ‪ B‬و ‪ C‬ﻋﻠﻰ اﻟﺘﻮاﻟﻲ‬

‫] ‪[ 2π‬‬

‫‪−2i‬‬ ‫‪−π‬‬ ‫' ‪z "− z‬‬ ‫≡ ) ‪≡ arg m ≡ arg(−i‬‬ ‫‪arg OC ; AB ≡ arg‬‬ ‫‪2‬‬ ‫' ‪z "+ z‬‬ ‫‪2‬‬ ‫‪m‬‬

‫)‬

‫(‬

‫إذن ) ‪(OC ) ⊥ ( AB‬‬ ‫‪−2i‬‬ ‫‪2‬‬ ‫‪2‬‬ ‫‪2‬‬ ‫=‬ ‫= " ‪ OC = z '+ z‬و ‪= 2‬‬ ‫=‬ ‫ﻟﺪﻳﻨﺎ ‪= 2‬‬ ‫‪m‬‬ ‫‪m‬‬ ‫‪2‬‬ ‫‪2‬‬

‫= ' ‪AB = z "− z‬‬

‫وﻣﻨﻪ ‪AB = OC‬‬ ‫إذن اﻟﺮﺑﺎﻋﻲ ‪ OABC‬ﻣﺮﺑﻊ ‪.‬‬ ‫اﻟﺘﻤﺮﻳﻦ‪4‬‬ ‫‪ -1‬ﺡﺪد ﺕﻤﺜﻴﻼ ﺑﺎراﻣﺘﺮﻳﺎ ﻟﻠﻤﺴﺘﻘﻴﻢ ) ‪. ( D‬‬ ‫اﻟﻤﺴﺘﻘﻴﻢ ) ‪ ( D‬ﻣﺎر ﻣﻦ ) ‪ A ( 2;0;2‬و ﻋﻤﻮدي ﻋﻠﻰ اﻟﻤﺴﺘﻮى ) ‪ ( P‬ذا اﻟﻤﻌﺎدﻟﺔ ‪. x + y − z + 3 = 0‬‬

‫وﻣﻨﻪ اﻟﻤﺘﺠﻬﺔ )‪ u (1;1; −1‬اﻟﻤﻨﻈﻤﻴﺔ ﻋﻠﻰ ) ‪ ( P‬ﻣﻮﺟﻬﺔ ﻟـ ) ‪( D‬‬

‫إذن‬

‫‪x = 2 + t‬‬ ‫‪  y = t‬ﺕﻤﺜﻴﻞ ﺑﺎراﻣﺘﺮﻳﺎ ﻟﻠﻤﺴﺘﻘﻴﻢ ) ‪( D‬‬ ‫‪‬‬ ‫‪z = 2 − t‬‬

‫∈‪t‬‬

‫‪ -2‬ﻧﺤﺪد إﺡﺪاﺙﻴﺎت ‪. B‬‬

‫‪= 2 +t‬‬ ‫‪x = 3‬‬ ‫‪‬‬ ‫‪=t‬‬ ‫‪y =1‬‬ ‫‪⇔‬‬ ‫‪= 2 −t‬‬ ‫‪z =1‬‬ ‫‪−3= 0‬‬ ‫‪ t = 1‬‬

‫‪= 2 +t‬‬ ‫‪=t‬‬ ‫‪= 2 −t‬‬

‫‪x‬‬ ‫‪‬‬ ‫‪y‬‬ ‫‪⇔‬‬ ‫‪z‬‬ ‫‪+ y −z −3= 0‬‬ ‫‪3t‬‬

‫‪x‬‬ ‫‪‬‬ ‫‪y‬‬ ‫‪B (x ; y ;z ) ∈(D ) ∩ (P ) ⇔ ‬‬ ‫‪z‬‬ ‫‪ x‬‬

‫إذن )‪B ( 3;1;1‬‬

‫) ‪(S‬‬

‫‪ -3‬أ‪ -‬ﻧﺤﺪد ﺵﻌﺎع اﻟﻔﻠﻜﺔ‬ ‫ﻟﺪﻳﻨﺎ ‪= 3‬‬

‫‪2+0−2−3‬‬ ‫‪12 + ( −1) + 12‬‬ ‫‪2‬‬

‫= ) ) ‪AB = d ( A ; ( P‬‬ ‫‪2‬‬

‫‪3 + 22 = 7‬‬

‫ﻟﻴﻜﻦ ‪ r‬ﺵﻌﺎع اﻟﻔﻠﻜﺔ‬ ‫ب‪ -‬ﻧﺤﺪد ﻣﻌﺎدﻟﺔ دﻳﻜﺎرﺕﻴﺔ ﻟﻠﻔﻠﻜﺔ‬

‫=‪r‬‬

‫) ‪(S‬‬

‫‪( S ) : ( x − 2 )2 + y 2 + ( z − 2 ) = 7‬‬ ‫‪( S ) : x 2 + y 2 + z 2 − 4x − 4z + 1 = 0‬‬ ‫اﻟﻤﺴﺄﻟﺔ‬

‫(‬

‫)‬

‫‪ f ( x ) = ln 1 − x 3 ; x ≺ 0‬‬ ‫‪‬‬ ‫‪‬‬ ‫‪f ( x ) = 4x x − 3x 2 x ≥ 0‬‬ ‫‪ - 1‬أ‪ -‬ﻧﺒﻴﻦ أن اﻟﺪاﻟﺔ ‪ f‬ﻣﺘﺼﻠﺔ ﻓﻲ ‪.0‬‬

‫‪; f ( 0) = 0‬‬

‫‪lim+ f ( x ) = lim+ 4x x − 3x 2 = 0‬‬

‫‪x →0‬‬

‫‪x →0‬‬

‫(‬

‫)‬

‫; ‪lim− f ( x ) = lim− ln 1 − x 3 = 0‬‬ ‫‪x →0‬‬

‫) ‪ lim f ( x ) = lim f ( x ) = f ( 0‬اذن ‪ f‬ﻣﺘﺼﻠﺔ ﻓﻲ ‪.0‬‬ ‫‪x →0 −‬‬

‫‪x →0 +‬‬

‫ب‪ -‬ﻧﺒﻴﻦ أن اﻟﺪاﻟﺔ ‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺵﺘﻘﺎق ﻓﻲ ‪0‬‬

‫‪x x − 3x 2‬‬ ‫‪= lim+‬‬ ‫‪= lim+ x − 3x = 0‬‬ ‫‪x →0‬‬ ‫‪x →0‬‬ ‫‪x‬‬

‫) ‪(t = − x‬‬ ‫‪3‬‬

‫إذن‬

‫‪3 2‬‬

‫‪t =0‬‬

‫× ) ‪) = lim ln (1 + t‬‬ ‫‪t‬‬

‫‪+‬‬

‫(‬

‫‪ln 1 − x 3‬‬

‫‪t →0‬‬

‫‪x‬‬

‫‪= lim−‬‬ ‫‪x →0‬‬

‫)‪f ( x ) − f ( 0‬‬ ‫‪x −0‬‬ ‫)‪f ( x ) − f ( 0‬‬ ‫‪x −0‬‬

‫‪lim‬‬

‫‪x →0 +‬‬

‫‪lim−‬‬

‫‪x →0‬‬

‫‪ f‬ﻗﺎﺑﻠﺔ ﻟﻼﺵﺘﻘﺎق ﻓﻲ ‪ 0‬و ‪f ' ( 0 ) = 0‬‬

‫‪ -2‬ﻧﺒﻴﻦ أن ‪ f‬ﺕﻨﺎﻗﺼﻴﺔ ﻋﻠﻰ اﻟﻤﺠﺎﻟﻴﻦ [‪ ]−∞;0‬و [∞‪ [1; +‬و ﺕﺰاﻳﺪﻳﺔ ﻋﻠﻰ اﻟﻤﺠﺎل ]‪. [ 0;1‬‬ ‫*‬

‫)‬

‫(‬

‫‪− 6x = 4 x + 2 x − 6 x = 6 x 1 − x‬‬

‫‪2x‬‬ ‫‪x‬‬

‫‪∀x ∈ ]0; +∞[ f ' ( x ) = 4 x +‬‬

‫‪x →0‬‬

‫(‬

‫إﺵﺎرة ) ‪ f ' ( x‬ﻋﻠﻰ [∞‪ ]0;+‬هﻲ إﺵﺎرة )‬

‫‪. 1− x‬‬

‫ﻟﺪﻳﻨﺎ ‪ ∀x ∈ [ 0;1] 1 − x ≥ 0‬وﻣﻨﻪ ‪ f‬ﺕﺰاﻳﺪﻳﺔ ﻋﻠﻰ اﻟﻤﺠﺎل ]‪. [ 0;1‬‬ ‫‪ ∀x ∈ [1; +∞[ 1 − x ≤ 0‬و ﻣﻨﻪ‬ ‫*‬

‫‪−3x 2‬‬ ‫= ) ‪f '( x‬‬ ‫‪1− x 3‬‬ ‫ﻟﺪﻳﻨﺎ ‪0‬‬ ‫إذن‬

‫‪ f‬ﺕﻨﺎﻗﺼﻴﺔ ﻋﻠﻰ [∞‪[1;+‬‬

‫[‪∀x ∈ ]−∞;0‬‬

‫‪ ∀x ∈ ]−∞;0[ −3x 2 ≺ 0 ; 1 − x 3‬وﻣﻨﻪ ‪0‬‬

‫) ‪∀x ∈ ]−∞;0[ f ' ( x‬‬

‫‪ f‬ﺕﻨﺎﻗﺼﻴﺔ ﻋﻠﻰ [‪]−∞;0‬‬

‫‪ -3‬أ‪ -‬ﻧﺤﺴﺐ ) ‪lim f ( x‬‬

‫∞‪x →−‬‬

‫;‬

‫)‬

‫‪. lim f ( x‬‬ ‫∞‪x →+‬‬

‫‪ 4‬‬ ‫‪‬‬ ‫∞‪− 3  = −‬‬ ‫‪lim f ( x ) = lim x 2 ‬‬ ‫∞‪x →+‬‬ ‫∞‪x →+‬‬ ‫‪ x‬‬ ‫‪‬‬

‫(‬

‫)‬

‫∞‪lim f ( x ) = lim ln 1 − x 3 = +‬‬

‫∞‪x →−‬‬

‫∞‪x →−‬‬

‫)‬

‫ب‪ -‬ﻧﺘﺤﻘﻖ ﻣﻦ أﻧﻪ ﻟﻜﻞ ‪; x ≺ 0‬‬

‫(‬

‫‪ln 1 − x −3‬‬ ‫‪x‬‬

‫‪+‬‬

‫) ‪ln ( − x‬‬ ‫‪x‬‬

‫‪=3‬‬

‫) ‪f (x‬‬ ‫‪x‬‬

‫ﻟﻴﻜﻦ [‪x ∈ ]−∞;0‬‬

‫) ‪) = ln (1 − x ) = f ( x‬‬ ‫‪3‬‬

‫‪x‬‬

‫) ‪(1 − x −3‬‬

‫‪x‬‬

‫‪3‬‬

‫‪x‬‬

‫‪) = ln ( −x ) + ln (1 − x ) = ln ( −x‬‬ ‫‪−3‬‬

‫‪3‬‬

‫‪x‬‬

‫ج‪ -‬أدرس اﻟﻔﺮﻋﻴﻦ اﻟﻼﻧﻬﺎﺋﻴﻴﻦ ﻟﻠﻤﻨﺤﻨﻰ ) ‪. (C‬‬

‫∞‪lim f ( x ) = −‬‬

‫∞‪x →+‬‬

‫‪ 4‬‬ ‫‪‬‬ ‫‪= lim x ‬‬ ‫; ∞‪− 3  = −‬‬ ‫‪x →+∞  x‬‬ ‫‪‬‬

‫) ‪f (x‬‬ ‫‪x‬‬

‫‪lim‬‬

‫∞‪x →+‬‬

‫إذن ) ‪ (C‬ﻳﻘﺒﻞ ﻓﺮﻋﺎ ﺵﻠﺠﻤﻴﺎ ﻓﻲ اﺕﺠﺎﻩ ﻣﺤﻮر اﻷراﺕﻴﺐ‬

‫∞‪lim f ( x ) = +‬‬

‫∞‪x →−‬‬

‫(‬

‫)‬

‫‪1‬‬ ‫‪× ln 1 − x −3 = 0‬‬ ‫‪x‬‬

‫‪+‬‬

‫) ‪ln ( − x‬‬ ‫‪x‬‬

‫‪= lim 3‬‬ ‫∞‪x →−‬‬

‫) ‪f (x‬‬ ‫‪x‬‬

‫‪lim‬‬

‫∞‪x →−‬‬

‫إذن ) ‪ (C‬ﻳﻘﺒﻞ ﻓﺮﻋﺎ ﺵﻠﺠﻤﻴﺎ ﻓﻲ اﺕﺠﺎﻩ ﻣﺤﻮر اﻷﻓﺎﺹﻴﻞ‬ ‫‪ -4‬ﻧﻨﺸﺊ اﻟﻤﻨﺤﻨﻰ ) ‪. (C‬‬

‫‪16‬‬ ‫‪9‬‬

‫= ‪x‬‬

‫(‬

‫)‬

‫‪4x x − 3x 2 = 0 ⇔ x x 4 − 3 x = 0 ⇔ x = 0 ou‬‬

‫)‬

‫(‬

‫‪−3x 2 + x 3‬‬

‫) ‪(1 − x‬‬

‫‪3 2‬‬

‫= ) ‪∀x ∈ ]−∞;0[ f "( x‬‬

‫ﻋﻠﻰ [‪ ]−∞;0‬اﻟﻤﻨﺤﻨﻰ ) ‪ (C‬ﻳﻘﺒﻞ ﻧﻘﻄﺔ اﻧﻌﻄﺎف ﻓﻲ اﻟﻨﻘﻄﺔ ذات اﻷﻓﺼﻮل ‪− 3 2‬‬

‫(‬

‫‪ln 1 − x −3‬‬ ‫‪x‬‬

‫‪+‬‬

‫) ‪ln ( − x‬‬ ‫‪x‬‬

‫‪3‬‬

‫‪ -5‬أ‪ -‬ﻧﺒﻴﻦ أن ‪ h‬ﺕﻘﺎﺑﻞ ﻣﻦ [‪ ]−∞;0‬ﻧﺤﻮ ﻣﺠﺎل ‪ J‬ﻳﺠﻴﺐ ﺕﺤﺪﻳﺪﻩ ‪.‬‬ ‫ﻟﺪﻳﻨﺎ ‪ h‬ﻗﺼﻮر اﻟﺪاﻟﺔ ‪ f‬ﻋﻠﻰ اﻟﻤﺠﺎل [‪ ]−∞;0‬و ﻣﻨﻪ‬

‫‪ h‬ﻣﺘﺼﻠﺔ و ﺕﻨﺎﻗﺼﻴﺔ ﻗﻄﻌﺎ ﻋﻠﻰ [‪]−∞;0‬‬

‫و [∞‪ h (]−∞;0[) = ]0; +‬وﻣﻨﻪ ‪ h‬ﺕﻘﺎﺑﻞ ﻣﻦ [‪ ]−∞;0‬ﻧﺤﻮ اﻟﻤﺠﺎل [∞‪J = ]0; +‬‬

‫ب‪ -‬ﺡﺪد )‬

‫‪ h −1 ( x‬ﻟﻜﻞ ‪ x‬ﻣﻦ ‪. J‬‬

‫ﻟﻴﻜﻦ [∞‪ x ∈ ]0; +‬و [‪y ∈ ]−∞;0‬‬ ‫‪h −1 ( x ) = y ⇔ h ( y ) = x‬‬

‫)‬

‫(‬

‫‪⇔ ln 1 − y 3 = x‬‬ ‫‪⇔ y 3 = 1−e x‬‬ ‫) [∞‪x ∈ ]0; +‬‬ ‫إذن‬

‫[‪( y ∈ ]−∞;0‬‬

‫‪h −1 ( x ) = y ⇔ y = − 3 e x − 1‬‬ ‫[∞‪∀x ∈ ]0; +‬‬

‫‪h −1 ( x ) = − 3 e x − 1‬‬

‫‪ -6‬ﻧﻌﺘﺒﺮ اﻟﻤﺘﺘﺎﻟﻴﺔ ) ‪ (u n‬اﻟﻤﻌﺮﻓﺔ ﺑﻤﺎ ﻳﻠﻲ‪:‬‬

‫‪4‬‬ ‫‪9‬‬ ‫أ‪-‬‬

‫‪4‬‬ ‫ﻧﺒﻴﻦ ﺑﺎﻟﺘﺮﺟﻊ أن ‪≤ u n ≤ 1‬‬ ‫‪9‬‬

‫= ‪ u 0‬و ‪u n +1 = 4u n u n − 3u n2‬‬

‫∈ ‪∀n‬‬

‫∈ ‪∀n‬‬

‫‪4‬‬ ‫‪4‬‬ ‫ﻣﻦ أﺟﻞ ‪ n = 0‬ﻟﺪﻳﻨﺎ = ‪ u 0‬إذن ‪≤ u 0 ≤ 1‬‬ ‫‪9‬‬ ‫‪9‬‬ ‫‪4‬‬ ‫‪4‬‬ ‫ﻟﻨﻔﺘﺮض أن ‪ ≤ u n ≤ 1‬ﻟﻨﺒﻴﻦ أن ‪≤ u n +1 ≤ 1‬‬ ‫‪9‬‬ ‫‪9‬‬ ‫‪4‬‬ ‫ﻟﺪﻳﻨﺎ ‪ f‬ﺕﺰاﻳﺪﻳﺔ ﻋﻠﻰ ]‪ [ 0;1‬وﻣﻨﻪ )‪f ( ) ≤ f (u n ) ≤ f (1‬‬ ‫‪9‬‬ ‫‪4 16‬‬ ‫‪4‬‬ ‫=) ( ‪f‬‬ ‫و ﺑﺎﻟﺘﺎﻟﻲ ‪ ≤ u n +1 ≤ 1‬ﻷن ‪ f (1) = 1‬و‬ ‫‪9‬‬ ‫‪27‬‬ ‫‪9‬‬ ‫‪4‬‬ ‫إذن ‪≤ u n ≤ 1‬‬ ‫‪9‬‬

‫‪4 16‬‬ ‫;‬ ‫≺‬ ‫‪9 27‬‬

‫∈ ‪∀n‬‬

‫ﻧﺒﻴﻦ أن اﻟﻤﺘﺘﺎﻟﻴﺔ ) ‪ (u n‬ﺕﺰاﻳﺪﻳﺔ‪.‬‬

‫ب‪-‬‬

‫(‬ ‫)‪− 1‬‬

‫)‬

‫‪u n +1 − u n = 4u n u n − 3u n2 − u n = u n −3u n + 4 u n − 1‬‬

‫‪4‬‬ ‫ﻟﺪﻳﻨﺎ ‪≤ u n ≤ 1‬‬ ‫‪9‬‬

‫‪un‬‬

‫()‬

‫∈ ‪∀n‬‬

‫(‬

‫‪= u n −3 u n + 1‬‬

‫‪1 2‬‬ ‫∈ ‪ ∀n‬وﻣﻨﻪ ‪≺ ≤ u n ≤ 1‬‬ ‫‪3 3‬‬

‫وﺑﺎﻟﺘﺎﻟﻲ ‪u n − 1 ≤ 0 ; −3 u n + 1 ≺ 0‬‬ ‫إذن ‪u n +1 − u n ≥ 0‬‬

‫∈ ‪∀n‬‬ ‫وﻣﻨﻪ ) ‪ (u n‬ﺕﺰاﻳﺪﻳﺔ‪.‬‬

‫∈ ‪∀n‬‬

‫ج‪ -‬ﻧﺴﺘﻨﺘﺞ أن اﻟﻤﺘﺘﺎﻟﻴﺔ ) ‪ (u n‬ﻣﺘﻘﺎرﺑﺔ ﺙﻢ أﺡﺴﺐ ﻧﻬﺎﻳﺘﻬﺎ‪.‬‬ ‫ﺑﻤﺎ أن ) ‪ (u n‬ﺕﺰاﻳﺪﻳﺔ و ﻣﻜﺒﻮرة ﻓﺎن ) ‪ (u n‬ﻣﺘﻘﺎرﺑﺔ‪.‬‬

‫ﻟﺪﻳﻨﺎ ) ‪u n +1 = f (u n‬‬

‫‪ 9  9 ‬‬ ‫‪4 ‬‬ ‫‪;1‬‬ ‫ﻋﻠﻰ‬ ‫ﻣﺘﺼﻠﺔ‬ ‫‪f‬‬ ‫و‬ ‫‪f‬‬ ‫‪‬‬ ‫∈ ‪ ∀n‬و ‪ ;1  ⊂  ;1‬‬ ‫‪ 9 ‬‬ ‫‪4  4 ‬‬

‫‪4 ‬‬ ‫‪ lim u n‬هﻮ ﺡﻞ ﻟﻠﻤﻌﺎدﻟﺔ ‪ f ( l ) = l‬ﻓﻲ ‪ 9 ;1‬‬

‫)‬

‫‪f ( l ) = l ⇔ 4l l − 3l 2 − l = 0‬‬

‫‪l −l = 0‬‬ ‫‪1‬‬ ‫‪9‬‬

‫= ‪l‬‬

‫()‬

‫‪l = 1 ou‬‬

‫‪4 ‬‬ ‫وﺡﻴﺚ ‪ l ∈  ;1‬ﻓﺎن ‪l = 1‬‬ ‫‪9 ‬‬

‫(‬

‫‪⇔ l −3 l + 1‬‬ ‫‪⇔ l = 0 ou‬‬

‫وﻣﻨﻪ ‪lim u n = 1‬‬

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