SOLUTION: x(to the 4th power)-6x(squared)-27=0. whats the answer?

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Question 551480: x(to the 4th power)-6x(squared)-27=0. whats the answer?
Found 2 solutions by josmiceli, KMST:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+x%5E4+-+6x%5E2+-+27+=+0+
Make the substitution +z+=+x%5E2+
+z%5E2+-+6z+-+27+-+0+
+%28+z+-+9+%29%2A%28+z+%2B+3+%29+=+0+ ( I solved by looking at it )
+z+=+9+
+x%5E2+=+9+
+x+=+3+
+x+=+-3+
and
+z+=+-3+
+x%5E2+=+-3+
+x+=+sqrt%28-3+%29+
+x+=+sqrt%28-1%29%2Asqrt%283%29+
+x+=+sqrt%283%29%2Ai+
and
+x+=+-sqrt%283%29%2Ai+
-----------------
The solutions are:
+x+=+3+
+x+=+-3+
+x+=+sqrt%283%29%2Ai+
+x+=+-sqrt%283%29%2Ai+



Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E4-6x%5E2-27=0
Factoring
%28x%5E2-9%29%28x%5E2%2B3%29=0
Two of 4 solutions come from
x%5E2-9=0 --> x=3 and x=-3
The other two solutions come from
x%5E2%2B3=0 --> x=i%2Asqrt%283%29 and x=-i%2Asqrt%283%29