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# Vector calculus question

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1. Hi,

I'm stuck on the question that is attached. I can follow it up until the second from last line that contains the inequality

4 x (1/2)(g^2) ...

I dont understand where this inequality has come from and why one side is multiplied by four and the other side has been squared.

Any help would be appreciated
Attached Images

2. The discriminant for no real roots needs to satisfy b^2-4ac<0 or 4ac>b^2 (remember this is for t>0 so we can divide by t in the cubic given to get a quadratic).
3. (Original post by Math12345)
The discriminant for no real roots needs to satisfy b^2-4ac<0 or 4ac>b^2 (remember this is for t>0 so we can divide by t in the cubic given to get a quadratic).
Thanks for that, appreciate the help!

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