$\displaystyle Sup {x \in \Re: x^2+4x+1<0}$
I'm not sure how to get the set brackets up so here it is without the math bits next to it:
Sup {x \in \Re: x^2+4x+1<0}
What's the answer?
Well I can use the quadratic formula to get $\displaystyle \frac{-4 + \sqrt {4^2-4}}{{2}}=\frac{-4 + \sqrt{12}}{2}=\frac{-4 + 2 \sqrt 2}{2}=-2+\sqrt 2$.
I was just thinking that the answer would be zero since the greatest value of $\displaystyle x^2+4x+1$ is 0. I can see what I was doing wrong now.
cheers!