Menu Close

decompose-inside-R-x-the-fraction-1-F-x-1-x-3-x-2-3-2-F-x-1-x-1-4-x-3-4-




Question Number 88032 by mathmax by abdo last updated on 07/Apr/20
decompose inside R(x) the fraction  1) F(x) =(1/(x^3 (x−2)^3 ))  2) F(x) =(1/((x+1)^4 (x−3)^4 ))
decomposeinsideR(x)thefraction1)F(x)=1x3(x2)32)F(x)=1(x+1)4(x3)4
Commented by jagoll last updated on 08/Apr/20
what is R(x)? remainder?
whatisR(x)?remainder?
Commented by abdomathmax last updated on 10/Apr/20
space of rational fractions
spaceofrationalfractions
Commented by abdomathmax last updated on 10/Apr/20
1)F(x) =(1/8)(((x−(x−2))^3 )/(x^3 (x−2)^3 )) ⇒  8F(x)?=((x^3  −3x^2 (x−2) +3x(x−2)^2  −(x−2)^3 )/(x^3 (x−2)^3 ))  =((x^3  +3x(x−2)(−x+x−2) −(x−2)^3 )/(x^3 (x−2)^3 ))  =((x^3  −6x(x−2)−(x−2)^3 )/(x^3 (x−2)^3 ))  =(1/((x−2)^3 )) −(6/(x^2 (x−2)^2 ))−(1/x^3 )  =(1/((x−2)^3 ))−(1/x^3 ) −(3/2){(((x−(x−2))^2 )/(x^2 (x−2)^2 ))}  =(1/((x−2)^3 ))−(1/x^3 )−(3/2){ ((x^2 −2x(x−2) +(x−2)^2 )/(x^2 (x−2)^2 ))}  =(1/((x−2)^3 ))−(1/x^3 )−(3/(2(x−2)^2 )) +(6/(x(x−2))) +(3/(2x^2 ))  =(1/((x−2)^3 ))−(1/x^3 )−(3/(2(x−2)^2 )) −3((1/x)−(1/(x−2))) +(3/(2x^2 ))  =−(3/x) +(3/(x−2)) +(3/(2x^2 ))−(3/(2(x−2)^2 ))−(1/x^3 ) +(1/((x−2)^3 )) =8F(x)
1)F(x)=18(x(x2))3x3(x2)38F(x)?=x33x2(x2)+3x(x2)2(x2)3x3(x2)3=x3+3x(x2)(x+x2)(x2)3x3(x2)3=x36x(x2)(x2)3x3(x2)3=1(x2)36x2(x2)21x3=1(x2)31x332{(x(x2))2x2(x2)2}=1(x2)31x332{x22x(x2)+(x2)2x2(x2)2}=1(x2)31x332(x2)2+6x(x2)+32x2=1(x2)31x332(x2)23(1x1x2)+32x2=3x+3x2+32x232(x2)21x3+1(x2)3=8F(x)
Commented by mathmax by abdo last updated on 10/Apr/20
error of calculus  8F(x)=(1/((x−2)^3 ))−(1/x^3 )−(3/(2(x−2)^2 )) +(3/(x(x−2)))−(3/(2x^2 ))  =(1/((x−2)^3 ))−(1/x^3 )−(3/(2(x−2)^2 )) −(3/2)((1/x)−(1/(x−2)))−(3/(2x^2 ))  F(x)=(1/8){(1/((x−2)^3 ))−(1/x^3 )−(3/(2(x−2)^2 ))−(3/(2x)) +(3/(2(x−2)))−(3/(2x^2 ))}
errorofcalculus8F(x)=1(x2)31x332(x2)2+3x(x2)32x2=1(x2)31x332(x2)232(1x1x2)32x2F(x)=18{1(x2)31x332(x2)232x+32(x2)32x2}
Commented by mathmax by abdo last updated on 10/Apr/20
2)F(x)=(1/4^4 )(({(x+1)−(x−3)}^4 )/((x+1)^4 (x−3)^4 ))  ⇒4^4  F(x)=(({(x+1)^2 −2(x+1)(x−3)+(x−3)^2 }^2 )/((x+1)^4 (x−3)^4 ))  we use the identity (a+b+c)^2 =a^2  +b^2  +c^2  +2(ab +bc +ca) ⇒  4^4  F(x)=(((x+1)^4  +4(x+1)^2 (x−3)^2  +(x−3)^4  +2{ −2(x+1)^3 (x−3)+(x+1)^2 (x−3)^2 −2(x+1)(x−3)^3 })/((x+1)^4 (x−3)^4 ))  =(1/((x−3)^4 )) +(4/((x+1)^2 (x−3)^2 )) +(1/((x+1)^4 )) −(4/((x+1)(x−3)^3 )) +(2/((x+1)^2 (x−3)^2 ))−(4/((x+1)^3 (x−3)))  also we have (4/((x+1)^2 (x−3)^2 )) =(1/4){((((x+1)−(x−3))^2 )/((x+1)^2 (x−3)^2 ))}  =(1/4){(((x+1)^2 −2(x+1)(x−3) +(x−3)^2 )/((x+1)^2 (x−3)^2 ))}  =(1/4){ (1/((x−3)^2 )) −(2/((x+1)(x−3))) +(1/((x+1)^2 ))}  =(1/(4(x−3)^2 ))+(1/8)((1/(x+1))−(1/(x−3)))+(1/(4(x+1)^2 ))  =(1/(4(x−3)^2 )) +(1/(8(x+1)))−(1/(8(x−3)))+(1/(4(x+1)^2 ))  −(4/((x+1)(x−3)^3 ))−(4/((x+1)^3 (x−3))) =−(4/((x+1)(x−3)))((1/((x−3)^2 ))+(1/((x+1)^2 )))  =((1/(x+1))−(1/(x−3)))((1/((x−3)^2 ))+(1/((x+1)^2 )))  =(1/((x+1)(x−3)^2 )) +(1/((x+1)^3 ))−(1/((x−3)^3 ))−(1/((x−3)(x+1)^2 ))  =(1/((x+1)(x−3))){(1/(x−3))−(1/(x+1))}+(1/((x+1)^3 ))−(1/((x−3)^3 ))  =−(1/4)((1/(x+1))−(1/(x−3)))((1/(x−3))−(1/(x+1)))+(1/((x+1)^3 ))−(1/((x−3)^3 ))  =−(1/4)((1/((x+1)(x−3)))−(1/((x+1)^2 ))−(1/((x−3)^2 ))+(1/((x−3)(x+1))))+(1/((x+1)^3 ))−(1/((x−3)^3 ))  ....
2)F(x)=144{(x+1)(x3)}4(x+1)4(x3)444F(x)={(x+1)22(x+1)(x3)+(x3)2}2(x+1)4(x3)4weusetheidentity(a+b+c)2=a2+b2+c2+2(ab+bc+ca)44F(x)=(x+1)4+4(x+1)2(x3)2+(x3)4+2{2(x+1)3(x3)+(x+1)2(x3)22(x+1)(x3)3}(x+1)4(x3)4=1(x3)4+4(x+1)2(x3)2+1(x+1)44(x+1)(x3)3+2(x+1)2(x3)24(x+1)3(x3)alsowehave4(x+1)2(x3)2=14{((x+1)(x3))2(x+1)2(x3)2}=14{(x+1)22(x+1)(x3)+(x3)2(x+1)2(x3)2}=14{1(x3)22(x+1)(x3)+1(x+1)2}=14(x3)2+18(1x+11x3)+14(x+1)2=14(x3)2+18(x+1)18(x3)+14(x+1)24(x+1)(x3)34(x+1)3(x3)=4(x+1)(x3)(1(x3)2+1(x+1)2)=(1x+11x3)(1(x3)2+1(x+1)2)=1(x+1)(x3)2+1(x+1)31(x3)31(x3)(x+1)2=1(x+1)(x3){1x31x+1}+1(x+1)31(x3)3=14(1x+11x3)(1x31x+1)+1(x+1)31(x3)3=14(1(x+1)(x3)1(x+1)21(x3)2+1(x3)(x+1))+1(x+1)31(x3)3.
Commented by abdomathmax last updated on 10/Apr/20
1) another way  we detemine D_2 f(0) with  f(x)=(1/((x−2)^3 )) ⇒f(x)=f(0) +(x/(1!))f^((1)) (0)+(x^2 /(2!))f^((2)) (0)  +x^3 ξ(x)  f(0)=−(1/8)  f(x)=(x−2)^(−3)  ⇒f^′ (x)=−3(x−2)^(−4)  ⇒  f^′ (0)=−3(−2)^(−4)  =((−3)/2^4 ) =−(3/(16))  f^((2)) (0) =12(x−2)^(−5)  ⇒f^((2)) (0) =((12)/((−2)^5 )) =−((12)/2^5 )  =−((12)/(32)) =−(3/8)  decomposition of F is  F(x)=Σ_(i=1) ^3  (a_i /x^i ) +Σ_(i=1) ^3  (b_i /((x−2)^i ))  we have  F(x)=(1/x^3 )(−(1/8)−(3/(16))x−(3/(16))x^2  +x^3 ξ(x))  =−(1/(8x^3 ))−(3/(16x^2 ))−(3/(16x)) +ξ(x) ⇒a_1 =−(3/(16))  a_2 =−(3/(16))  and a_3 =−(1/8)  let find the b_i  we do the  changement x−2 =t ⇒  F(x)=(1/(t^3 (t+2)^3 ))  and find D_2 (0) for g(t)=(t+2)^(−3)   g(t)=g(0)+t g^′ (0) +(t^2 /2)g^((2)) (0) +t^3 δ(x)  g(0)=(1/8)  ,   g^′ (t)=−3(t+2)^(−4)  ⇒g^′ (0)=((−3)/(16))  g^((2)) (0) =12(t+2)^(−5)  ⇒g^((2)) (0)=((12)/2^5 ) =((12)/(32)) =(3/8)  F(x)=(1/t^3 ){(1/8)−(3/(16))t +(3/(16))t^2  +t^3 δ(t)}  =(1/(8t^3 )) −(3/(16t^2 )) +(3/(16t)) +δ(t)  =(1/(8(x−2)^3 ))−(3/(16(x−2)^2 ))+(3/(16(x−2))) +δ(t) ⇒  b_1 =(3/(16)) , b_2 =−(3/(26))  and b_3 =(1/8)  tbe coefficients are found
1)anotherwaywedetemineD2f(0)withf(x)=1(x2)3f(x)=f(0)+x1!f(1)(0)+x22!f(2)(0)+x3ξ(x)f(0)=18f(x)=(x2)3f(x)=3(x2)4f(0)=3(2)4=324=316f(2)(0)=12(x2)5f(2)(0)=12(2)5=1225=1232=38decompositionofFisF(x)=i=13aixi+i=13bi(x2)iwehaveF(x)=1x3(18316x316x2+x3ξ(x))=18x3316x2316x+ξ(x)a1=316a2=316anda3=18letfindthebiwedothechangementx2=tF(x)=1t3(t+2)3andfindD2(0)forg(t)=(t+2)3g(t)=g(0)+tg(0)+t22g(2)(0)+t3δ(x)g(0)=18,g(t)=3(t+2)4g(0)=316g(2)(0)=12(t+2)5g(2)(0)=1225=1232=38F(x)=1t3{18316t+316t2+t3δ(t)}=18t3316t2+316t+δ(t)=18(x2)3316(x2)2+316(x2)+δ(t)b1=316,b2=326andb3=18tbecoefficientsarefound
Commented by abdomathmax last updated on 10/Apr/20
b_2 =−(3/(16))
b2=316

Leave a Reply

Your email address will not be published. Required fields are marked *