SOLUTION: find all the zeros and state any multiplicity for the following: j(x)=x^4+7x^2-18

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Question 854652: find all the zeros and state any multiplicity for the following:
j(x)=x^4+7x^2-18
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use a substitution, u=x%5E2
j%28u%29=u%5E2%2B7u-18
j%28u%29=%28u-2%29%28u%2B9%29
j%28x%29=%28x%5E2-2%29%28x%5E2%2B9%29
j%28x%29=%28x-sqrt%282%29%29%28x%2Bsqrt%282%29%29%28x-3i%29%28x%2B3i%29
.
.
x=sqrt%282%29,1
x=-sqrt%282%29,1
x=3i,1
x=-3i,1