deletions | additions       diff --git a/untitled.tex b/untitled.tex  index c8f5517..a8e5425 100644  --- a/untitled.tex  +++ b/untitled.tex 
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Thus, $(c^2+d^2)\geq 4b.$\\  Note:$\left|a^2\right|=(c^2+d^2).$\\  So, $\left|a^2\right| \geq 4b.$\\  Therefore, the equation $\left|z^2\right| + Re(az) + b=0$ has a solution if and only if $\left|a^2\right| \geq 4b.$  \end{proof}  \end{problem}