SOLUTION: solve: x^4+5x^2+9

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Question 177076: solve: x^4+5x^2+9
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
You can't solve x%5E4%2B5x%5E2%2B9, because you haven't set your expression equal to anything. Now if what you meant was x%5E4%2B5x%5E2%2B9+=+0, THEN you have something that you can solve.

Let t+=+x%5E2, then x%5E4+%2B+5x%5E2+%2B+9+=+0 is equivalent to t%5E2+%2B+5t+%2B+9+=+0, which is a quadratic that needs to be solved with the quadratic formula:

t+=+%28-5+%2B-+sqrt%28+25-36+%29%29%2F2+=+%28-5+%2B-+i%2Asqrt%2811%29%29%2F2+

but t+=+x%5E2 so:

or

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