## solve x^4 - 6x^2 = 7

Complex numbers, rational functions, logarithms, sequences and series, matrix operations, etc.
sanman777
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### solve x^4 - 6x^2 = 7

solve x^4-6x^2=7

stapel_eliz
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solve x^4-6x^2=7
This is an equation in the form of a quadratic:

. . . . .$x^4\, -\, 6x^2\, -\, 7\, =\, 0$

. . . . .$(x^2)^2\, -\, 6(x^2)\, -\, 7\, =\, 0$

So factor the above just as you would factor the below:

. . . . .$y^2\, -\, 6y\, -\, 7\, =\, 0$

Then solve the two factors:

. . . . .$x^2\, +\, 1\, =\, 0\, \mbox{ or }\, x^2\, -\, 7\, =\, 0$

Whether you have two solutions or four will depend upon whether you've studied complex numbers yet.

If you get stuck, please reply with a clear listing of your work and reasoning so far. Thank you!