Hello. I was the Anon who asked the other day about the Lewis Carrol equasion. I want to thank you for your answer. I, however, believe that your calculator is malfunctioning. On three diffrent computers, I have inputed this equation. It's answer is {} insted of the answer you provided me. It also opens a graph, a thing it did not do when I first calculated the answer a few months ago. I do not know what is causing this, but it is happening. I also attempted with your french version, and it did the same thing as well. Either this is malfunctioning, or it is no longer powerful enough to calculate it. It is something that you may want to check. Thank you.
+118723 Well, I have checked using a hand held casio calculator and Wolfram|Alpha calculator and
Alan has checked using Mathcad.
It is correct to 12 significant figures. The last five digits have some rounding error. For most people's purposes this error would be insignificant.
+118723 $${{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,\small\textbf+\,}}{\mathtt{53}} = {\frac{{\mathtt{11}}}{{\mathtt{3}}}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{\,-\,}}{\frac{\left({\sqrt{{\mathtt{1\,335}}}}{\mathtt{\,\times\,}}{i}{\mathtt{\,\small\textbf+\,}}{\mathtt{21}}\right)}{{\mathtt{6}}}}\\
{\mathtt{x}} = {\frac{\left({\sqrt{{\mathtt{1\,335}}}}{\mathtt{\,\times\,}}{i}{\mathtt{\,-\,}}{\mathtt{21}}\right)}{{\mathtt{6}}}}\\
\end{array} \right\} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{\,-\,}}\left({\frac{{\mathtt{7}}}{{\mathtt{2}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{6.089\: \!608\: \!635\: \!484\: \!241\: \!2}}{i}\right)\\
{\mathtt{x}} = {\mathtt{\,-\,}}{\frac{{\mathtt{7}}}{{\mathtt{2}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{6.089\: \!608\: \!635\: \!484\: \!241\: \!2}}{i}\\
\end{array} \right\}$$
$$3x^2+21x+148=0\\\\
x=\frac{-21\pm\sqrt{1335}}{6}\qquad \mbox{That bit is correct}\\\\
\mbox{so it is only the coefficient of i that is in question}$$
From my hand held casio calculator it is 6.089608635 so to 10 significant figures it is correct.
Okay, from further checking it appears to be correct to 12 significant figures the last 5 digits may have rounding error.
If you want an exact answer your would leave it as a surd.
+33661 Here's the result as calculated to 50 decimal places by Mathcad's symbolic maths system:
Looks like the local calculator is accurate up to about 11 decimal places.
NB Looks like the image above has cut off the "i" in the decimal answer!
This is my answer, compleatly diffrent from yours for x^2+7x+53=11/3, which according to the calculator yealds {}:
+118723 Well, I have checked using a hand held casio calculator and Wolfram|Alpha calculator and
Alan has checked using Mathcad.
It is correct to 12 significant figures. The last five digits have some rounding error. For most people's purposes this error would be insignificant.
