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y=(-6/y)²-1

 Feb 13, 2015

Best Answer 

 #3
avatar+130477 
+5

Duh.....I should have seen right off that 3 was a "root"......over-reliance on technology is sometimes crippling......LOL!!!!!

 

 Feb 13, 2015
 #1
avatar+130477 
+5

Well...maybe we can.....

y=(-6/y)²-1         simpify

y = 36/y^2 - 1    multiply through by y^2

y^3 = 36 - y^2

And using the onsite solver, we have one real solution and two non-real solutions...

y3+y236=0{y=2(32)×i2y=2(32)×i2y=3}{y=22.8284271247461901iy=2+2.8284271247461901iy=3}

 

 Feb 13, 2015
 #2
avatar+118703 
+5

y=(-6/y)²-1

 

y=(6y)21y=36y21y3=36y2y0y3+y236=0

 

now I am going to use reaminder theorum to look for a factor

If y=3 then  27+9-36=0  great (y-3) is a factor and 3 is a root

 

(y3+y236)÷(y3)=y2+4y+12$Iusedpolynomialdivisiontogetthis$soy3+y236=(y3)(y2+4y+12)$Nowfindrootsof$y2+4y+12=1648<0$thereforetherearenorealrootstothis$so$Theonlyrealsolutionis$y=3

 

check

http://www.wolframalpha.com/input/?i=y^3%2By^2-36%3D0

 Feb 13, 2015
 #3
avatar+130477 
+5
Best Answer

Duh.....I should have seen right off that 3 was a "root"......over-reliance on technology is sometimes crippling......LOL!!!!!

 

CPhill Feb 13, 2015
 #4
avatar+118703 
0

Yes that is true :))

 Feb 13, 2015

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