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Solving an equation

  • Thread starter Ted123
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  • #1
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Solve the equation [tex]x^4 - x^2 = k[/tex] where [itex]k>0[/itex].

Am I being thick or how do I solve this for [itex]x[/itex]?

Factorising gives [tex]x^2(x^2-1)=k[/tex] but now where?
 

Answers and Replies

  • #2
HallsofIvy
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Let [itex]y= x^2[/itex] and that becomes a quadratic function:
[itex]y^2- y= k[/itex] or [itex]y^2- y- k= 0[/itex]. Solve that for y, then solve [itex]x^2= y[/itex] for x.
 

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