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Equation

X^6-X^3=2

 Jun 19, 2015

Best Answer 

 #1
avatar+125 
+8

y=x3

y2y=2{y=2y=1}

x3=2{x=(2(13)×3×i2(13))2x=(2(13)×3×i+2(13))2x=2(13)}{x=0.6299605249474366+1.0911236359724287ix=(0.6299605249474366+1.0911236359724287i)x=1.2599210498948732}

x3=1{x=(3×i1)2x=(3×i+1)2x=1}{x=(12+0.866025403785i)x=12+0.866025403785ix=1}

So the real solutions are:

  • x=2(13)
  • x=1
.
 Jun 19, 2015
 #1
avatar+125 
+8
Best Answer

y=x3

y2y=2{y=2y=1}

x3=2{x=(2(13)×3×i2(13))2x=(2(13)×3×i+2(13))2x=2(13)}{x=0.6299605249474366+1.0911236359724287ix=(0.6299605249474366+1.0911236359724287i)x=1.2599210498948732}

x3=1{x=(3×i1)2x=(3×i+1)2x=1}{x=(12+0.866025403785i)x=12+0.866025403785ix=1}

So the real solutions are:

  • x=2(13)
  • x=1
syllogist Jun 19, 2015
 #2
avatar+26396 
+5

Equation  X^6-X^3=2

x6x3=2we substitute and set z=x3then we have z2z=2z2z2=0z1,2=1±14(2)2z1,2=1±92z1,2=1±32z1=1+32=2z2=132=1x1=3z1=32=1.25992104989x1=1.25992104989x2=3z2=31=1x2=1

 

 Jun 19, 2015
 #3
avatar+118696 
+5

Syllogist is right :))

 

X6X3=2LetY=X3Y2Y=2$Completingthesquare$Y2Y+14=2+14(Y12)2=94Y12=±32Y12=32ORY12=32Y=2ORY=1X3=2ORX3=1X=32ORX=1

 

These are just the real solutions :)

 

Let me think about the complex solutions

I think they are

 

x=32e2πi3,x=32e2πi3,x=eπi3,andx=eπi3

 

I hope I didn't s***w that one up :/ 

 Jun 19, 2015

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