SOLUTION: solve x^4-13x^2+36=0

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Question 196269: solve x^4-13x^2+36=0
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!

Use a substitution.

Let , then



Factor the quadratic:



So, or , but if then hence and if then hence

Therefore the four roots of the quartic are

Checking the answer, either by substitution of each of the four values into the original equation or by multiplying:



to verify that the completely simplified expansion is identical to the original quartic trinomial is left as an exercise for the student.

John