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Question Number 142939 by Rasheed.Sindhi last updated on 07/Jun/21

Q#141663 by  ajfour sir reposted.       x^2 (x−12)(x−15)=k(x−16) ;k>0       Find x in terms of k.

You can't use 'macro parameter character #' in math mode x2(x12)(x15)=k(x16);k>0 Findxintermsofk.

Answered by Rasheed.Sindhi last updated on 07/Jun/21

{x^2 (x−12)(x−15)}/(x−16)=k  Quotient is k with no remainder.  Let p(x)=x^2 (x^2 −27x+180)                     =x^4 −27x^3 +180x^2 +0x+0  By synthetic division:   determinant (((16)),1,(−27),(180),0,0),(,,(    16),(−176),(64),(1024)),(,1,(−11),(     4),(64),(1024)))  p(x)=Q(x)D(x)+R  x^2 (x−12)(x−15)=   (x^3 −11x^2 +4x+64)(x−16)+1024  Neither the quotient is constant  nor the remainder is zero ∀ x  So this proves that the equation  has no solution.

{x2(x12)(x15)}/(x16)=k Quotientiskwithnoremainder. Letp(x)=x2(x227x+180) =x427x3+180x2+0x+0 Bysyntheticdivision: 16)12718000161766410241114641024 p(x)=Q(x)D(x)+R x2(x12)(x15)= (x311x2+4x+64)(x16)+1024 Neitherthequotientisconstant northeremainderiszerox Sothisprovesthattheequation hasnosolution.

Commented bymr W last updated on 07/Jun/21

i think it′s wrong somewhere sir.  y=x^2 (x−12)(x−15) is a curve passing  through (0,0),(12,0) and (15,0)  y=k(x−16) is a line passing through  (16,0) with inclination k.  from (16,0) we can draw two tangent  lines to the curve, say these tangent  lines have inclination k_1  and k_2 .  we know for k≤k_1  or k≥k_2 , the line  y=k(x−16) intersects the curve at  least at one point and at most at  four points. that means for  k≤k_1  or k≥k_2 , the equation  x^2 (x−12)(x−15)=k(x−16) has  at least one solution and at most  four solutions.

ithinkitswrongsomewheresir. y=x2(x12)(x15)isacurvepassing through(0,0),(12,0)and(15,0) y=k(x16)isalinepassingthrough (16,0)withinclinationk. from(16,0)wecandrawtwotangent linestothecurve,saythesetangent lineshaveinclinationk1andk2. weknowforkk1orkk2,theline y=k(x16)intersectsthecurveat leastatonepointandatmostat fourpoints.thatmeansfor kk1orkk2,theequation x2(x12)(x15)=k(x16)has atleastonesolutionandatmost foursolutions.

Commented bymr W last updated on 07/Jun/21

Commented byRasheed.Sindhi last updated on 08/Jun/21

ThanX for your Efforts Sir!  Perhaps my logic is only valid for  integer k(?).

ThanXforyourEffortsSir! Perhapsmylogicisonlyvalidfor integerk(?).

Commented bymr W last updated on 08/Jun/21

the question doesn′t request if  x^2 (x−12)(x−15) can be expressed as  k(x−16) for any values of x, but only  asks if one or more values of x exist  such that x^2 (x−12)(x−15)=k(x−16).

thequestiondoesntrequestif x2(x12)(x15)canbeexpressedas k(x16)foranyvaluesofx,butonly asksifoneormorevaluesofxexist suchthatx2(x12)(x15)=k(x16).

Commented byRasheed.Sindhi last updated on 08/Jun/21

OK Sir, ThanX again.

OKSir,ThanXagain.

Answered by Rasheed.Sindhi last updated on 07/Jun/21

     x^2 (x−12)(x−15)=k(x−16) ;k>0  This means :     When x^2 (x−12)(x−15) is divided  by x−16, The quotient is k(>0) and  the remainder is 0  But we can verify that the remainder  R is:         R=(16)^2 (16−12)(16−15)              =256.4.1=1024≠0  So for any value of x the remainder  can′t be zero.  This proves that the above equation  can′t be solved (even in terms of k>0.)

x2(x12)(x15)=k(x16);k>0 Thismeans: Whenx2(x12)(x15)isdivided byx16,Thequotientisk(>0)and theremainderis0 Butwecanverifythattheremainder Ris: R=(16)2(1612)(1615) =256.4.1=10240 Soforanyvalueofxtheremainder cantbezero. Thisprovesthattheaboveequation cantbesolved(evenintermsofk>0.)

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