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Question Number 77885 by behi83417@gmail.com last updated on 11/Jan/20

solve for : x  1.(√((x−a)(x−b)))+(√((x−b)(x−c)))+(√((x−c)(x−a)))=d  [a,b,c,d∈R  try for:  a=4,b=3,c=2,d=1]  2. (x−a^2 )(√(x−a))+(x−a)(√(x−a^2 ))=a^2 +a+1  3. (x−a^2 )(√(x^2 −a))+(x^2 −a)(√(x−a^2 ))=a^2 +a+1  [a∈R  try for: a=(1/2) ]

solvefor:x1.(xa)(xb)+(xb)(xc)+(xc)(xa)=d[a,b,c,dRtryfor:a=4,b=3,c=2,d=1]2.(xa2)xa+(xa)xa2=a2+a+13.(xa2)x2a+(x2a)xa2=a2+a+1[aRtryfor:a=12]

Answered by jagoll last updated on 12/Jan/20

1. (√((x−4)(x−3)))+(√((x−3)(x−2)))=1−(√((x−2)(x−4)))  squaring  (x−3){x−4+x−2}+2(x−3)(√((x−4)(x−2)))=1+(x−4)(x−2)−2(√((x−4)(x−2)))  (x−3){2x−4+(√((x−4)(x−2))) }=1+(x−4)(x−2)−2(√((x−4)(x−2)))  let u = x−4   ⇔ (u−1){2u+4+(√(u(u+2)))}=1+u(u+2)−2(√(u(u+2)))  tobe continiu

1.(x4)(x3)+(x3)(x2)=1(x2)(x4)squaring(x3){x4+x2}+2(x3)(x4)(x2)=1+(x4)(x2)2(x4)(x2)(x3){2x4+(x4)(x2)}=1+(x4)(x2)2(x4)(x2)letu=x4(u1){2u+4+u(u+2)}=1+u(u+2)2u(u+2)tobecontiniu

Commented by mr W last updated on 12/Jan/20

dead−end street!  it leads to an 8−th order equation which  is not solvable.

deadendstreet!itleadstoan8thorderequationwhichisnotsolvable.

Commented by jagoll last updated on 12/Jan/20

hahaha....thanks sir

hahaha....thankssir

Commented by behi83417@gmail.com last updated on 12/Jan/20

dear master:mrW! thanks.  I hope and wait for any try by you, sir.

dearmaster:mrW!thanks.Ihopeandwaitforanytrybyyou,sir.

Commented by mr W last updated on 12/Jan/20

i don′t think a general solution (formula)  is possible.  assume a≥b≥c, we can say:  if d<(√((a−c)×min(a−b,b−c))) ⇒no solution.  if d≥(√((a−c)×min(a−b,b−c)))  one or two solutions exist which lie  in the range x≤c or x≥a. but a formula  for the roots is not possible.  as for the example a=4,b=3,c=2,  (√((4−2)×min(1,1)))=(√2)  therefore for d=1<(√2) there is no solution.  see diagram.  MJS sir has given the same statement.

idontthinkageneralsolution(formula)ispossible.assumeabc,wecansay:ifd<(ac)×min(ab,bc)nosolution.ifd(ac)×min(ab,bc)oneortwosolutionsexistwhichlieintherangexcorxa.butaformulafortherootsisnotpossible.asfortheexamplea=4,b=3,c=2,(42)×min(1,1)=2thereforeford=1<2thereisnosolution.seediagram.MJSsirhasgiventhesamestatement.

Commented by mr W last updated on 12/Jan/20

Commented by mr W last updated on 12/Jan/20

curve f(x) stands for  f(x)=(√((x−a)(x−b)))+(√((x−b)(x−c)))+(√((x−c)(x−a)))  and  d_(min) =(√((a−c)×min(a−b,b−c)))  solution for f(x)=d exists when  d≥d_(min) .

curvef(x)standsforf(x)=(xa)(xb)+(xb)(xc)+(xc)(xa)anddmin=(ac)×min(ab,bc)solutionforf(x)=dexistswhenddmin.

Commented by mr W last updated on 12/Jan/20

following is an example with  a=5,b=3,c=2.  for d=4: two solutions  for d=2.5: one solution.

followingisanexamplewitha=5,b=3,c=2.ford=4:twosolutionsford=2.5:onesolution.

Commented by mr W last updated on 12/Jan/20

Commented by mr W last updated on 12/Jan/20

Commented by behi83417@gmail.com last updated on 12/Jan/20

thank you very much dear master.  it is perfect sir.  great solution by great man!

thankyouverymuchdearmaster.itisperfectsir.greatsolutionbygreatman!

Answered by MJS last updated on 12/Jan/20

1.  let a≤b≤c; p≤q  (x−p)(x−q)≥0 ⇒ x≤p∨x≥q  ⇒  (x≤a∨x≥b)∧(x≤b∨x≥c)∧(x≤a∨x≥c)  ⇒  x≤a∨x≥c  ⇒  the minimum of  (√((x−a)(x−b)))+(√((x−b)(x−c)))+(√((x−c)(x−a)))  is either at x=a or x=c and thus its value  is either (√((a−b)(a−c))) or (√((c−a)(c−b)))  is (√((a−b)(a−c))) if a+c≥2b  or (√((c−a)(c−b))) if a+c≤2b    with a=4, b=3, c=2 the minimum is (√2)  ⇒ no solution for d=1

1.letabc;pq(xp)(xq)0xpxq(xaxb)(xbxc)(xaxc)xaxctheminimumof(xa)(xb)+(xb)(xc)+(xc)(xa)iseitheratx=aorx=candthusitsvalueiseither(ab)(ac)or(ca)(cb)is(ab)(ac)ifa+c2bor(ca)(cb)ifa+c2bwitha=4,b=3,c=2theminimumis2nosolutionford=1

Commented by behi83417@gmail.com last updated on 12/Jan/20

dear proph :MJS! thank you very much  sir.is there any chance to find: x in  terms of :a,b,c,d?

dearproph:MJS!thankyouverymuchsir.isthereanychancetofind:xintermsof:a,b,c,d?

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