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Q-solve-x-3-x-x-




Question Number 84515 by M±th+et£s last updated on 13/Mar/20
Q.solve  x^3 −x=x!
Q.solvex3x=x!
Answered by mr W last updated on 13/Mar/20
(x+1)x(x−1)=x(x−1)(x−2)!  x≠0, x≠1  ⇒x+1=(x−2)!  let t=x−2  ⇒t+3=t!  ⇒t=3  ⇒x=3+2=5
(x+1)x(x1)=x(x1)(x2)!x0,x1x+1=(x2)!lett=x2t+3=t!t=3x=3+2=5
Commented by mr W last updated on 14/Mar/20
at t=2:  t+3=5, t!=2 ⇒t+3>t!  at t=4:  t+3=7, t!=24 ⇒t+3<t!  that means between t=2 and t=4 there  is a point for t+3=t!. we can check  with t=3: t+3=6=t!=6. i.e. t=3 is  a solution and the only solution,  because upon t=4, t! ≫t+3.
att=2:t+3=5,t!=2t+3>t!att=4:t+3=7,t!=24t+3<t!thatmeansbetweent=2andt=4thereisapointfort+3=t!.wecancheckwitht=3:t+3=6=t!=6.i.e.t=3isasolutionandtheonlysolution,becauseupont=4,t!t+3.
Commented by M±th+et£s last updated on 14/Mar/20
thank you sir   but how did you get that  t+3=t!  t=3    ??
thankyousirbuthowdidyougetthatt+3=t!t=3??
Commented by M±th+et£s last updated on 14/Mar/20
god bless you sir
godblessyousir

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