SOLUTION: Please solve this problem for me! find all real and complex roots x^(4)-18x^2+32=0

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Question 768116: Please solve this problem for me!
find all real and complex roots

x^(4)-18x^2+32=0
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +z+=+x%5E2+
+x%5E4+-+18x%5E2+%2B+32+=+0+
+z%5E2+-+18z+%2B+32+=+0+
I see by looking at this that +2%2A16+=+32+
and also +2+%2B+16+=+18+, so I can get:
+%28+z+-+2+%29%2A%28+z+-+16+%29+=+0+
+z+=+2+
+z+=+16+
--------------
+z+=+x%5E2+
+x%5E2+=+2+
+x+=+sqrt%28+2+%29+
+x+=+-sqrt%28+2+%29+
and
+x%5E2+=+16+
+x+=+4+
+x+=+-4+
--------------
You can check the 4 roots by
plugging them back into the equation