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Question Number 59102 by Tawa1 last updated on 04/May/19

use remainder theorem to factorize completetly the expression       x^3 (y − z) + y^3 (z − x) + z^3 (x − y)

useremaindertheoremtofactorizecompletetlytheexpressionx3(yz)+y3(zx)+z3(xy)

Answered by tanmay last updated on 04/May/19

E=0 when x=y so (x−y)is factor (E=given expression)  similarly (y−z) and (z−x)  x^3 (y−z)+y^3 (z−x)+z^3 (x−y)  =(x−y)(y−z)(z−x)(symmetric function degree one)  =k(x−y)(y−z)(z−x)(x+y+z)  now to find value of k  in expression E  the coefficient of x^3 y=1  in derived expression the coefficuent of   x^3 y=−k  {kx×y×−x×x→−kx^3 y}  so answer  =(−1)×(x−y)(y−z)(z−x)(x+y+z)    recheck  x^3 (y−z)+y^3 (z−x)+z^3 (x−y)  =x^3 (y−z)+yz(y^2 −z^2 )−x(y^3 −z^3 )  =(y−z)[x^3 +y^2 z+yz^2 −xy^2 −xyz−xz^2 )  =(y−z)[−x(z^2 −x^2 )+yz(z−x)+y^2 (z−x)]  =(y−z)(z−x)[−xz−x^2 +yz+y^2 ]  =(y−z)(z−x)[−z(x−y)−(x+y)(x−y)]  =(x−y)(y−z)(z−x)(−x−y−z)  =(−1)×(x−y)(y−z)(z+x)(x+y+z)

E=0whenx=yso(xy)isfactor(E=givenexpression)similarly(yz)and(zx)x3(yz)+y3(zx)+z3(xy)=(xy)(yz)(zx)(symmetricfunctiondegreeone)=k(xy)(yz)(zx)(x+y+z)nowtofindvalueofkinexpressionEthecoefficientofx3y=1inderivedexpressionthecoefficuentofx3y=k{kx×y×x×xkx3y}soanswer=(1)×(xy)(yz)(zx)(x+y+z)recheckx3(yz)+y3(zx)+z3(xy)=x3(yz)+yz(y2z2)x(y3z3)=(yz)[x3+y2z+yz2xy2xyzxz2)=(yz)[x(z2x2)+yz(zx)+y2(zx)]=(yz)(zx)[xzx2+yz+y2]=(yz)(zx)[z(xy)(x+y)(xy)]=(xy)(yz)(zx)(xyz)=(1)×(xy)(yz)(z+x)(x+y+z)

Commented by Tawa1 last updated on 21/Jul/19

God bless you sir

Godblessyousir

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