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1-decompose-F-x-1-x-2-4-x-3-2-2-calculate-4-dx-x-2-4-x-3-2-




Question Number 33589 by abdo imad last updated on 19/Apr/18
1) decompose F(x) =   (1/((x^2 +4)(x−3)^2 ))  2) calculate  ∫_4 ^(+∞)     (dx/((x^2 +4)(x−3)^2 )) .
1)decomposeF(x)=1(x2+4)(x3)22)calculate4+dx(x2+4)(x3)2.
Commented by math khazana by abdo last updated on 22/Apr/18
F(x)= (a/(x−3)) +(b/((x−3)^2 )) +((cx+d)/(x^2  +4))  b =lim_(x→3) (x−3)^2 F(x)= (1/(13))  lim_(x→+∞) xF(x)=0 =a+c ⇒c=−a ⇒  F(x)= (a/(x−3)) +(1/(13(x−3)^2 )) +((−ax +d)/(x^2  +4))  F(0) = (1/(36)) = ((−a)/3) + (1/(117))  +(d/4) ⇒1=−12a +((36)/(117)) +9d  ⇒ −12a +9d = 1−((36)/(117)) = ((81)/(117))  F(2)= (1/8) = −a +(1/(13)) +((−2a+d)/8) ⇒  1= −8a +(8/(13)) −2a +d =−10a +d +(8/(13)) ⇒  −10a +d = 1−(8/(13)) = (5/(13)) we get tbe system  −12a +9d = ((81)/(117)) and  −10a +d =(5/(13)) ⇒  −90a +9d = ((45)/(13)) ⇒ 78a = ((81)/(117)) −((45)/(13)) ⇒  a= (1/(78))( ((81)/(117)) −((45)/(13))).....be continued....
F(x)=ax3+b(x3)2+cx+dx2+4b=limx3(x3)2F(x)=113limx+xF(x)=0=a+cc=aF(x)=ax3+113(x3)2+ax+dx2+4F(0)=136=a3+1117+d41=12a+36117+9d12a+9d=136117=81117F(2)=18=a+113+2a+d81=8a+8132a+d=10a+d+81310a+d=1813=513wegettbesystem12a+9d=81117and10a+d=51390a+9d=451378a=811174513a=178(811174513)..becontinued.

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