SOLUTION: Hello can someone show me how to write the square root of -9 +8 (which is not under the square root sign as a comples number in standard form. and is x^2-x-1 a prime quadratic

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Question 719865: Hello can someone show me how to write the square root of -9 +8 (which is not under the square root sign as a comples number in standard form.
and is x^2-x-1 a prime quadratic .what is a prime qudratic.Thanks
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
sqrt%28-9%29%2B8
sqrt%289%2A%28-1%29%29%2B8
sqrt%289%29%2Asqrt%28-1%29%2B8
3*i+8
8 + 3i

If the discriminant, b%5E2-4ac, is a perfect square then the quadratic will factor (i.e. it is not prime). If the discriminant is not a perfect square then the quadratic is prime.

For x%5E2-x-1 the discriminant is:
%28-1%29%5E2-4%281%29%28-1%29+=+1-4%281%29%28-1%29+=+1%2B4+=+5
5 is not a perfect square so x%5E2-x-1 is prime.