# What the error in writing this equation by latex?

\begin{eqnarray*}
f(\lambda x+(1−\lambda)y)\leq \lambda f(x)+(1−\lambda)f(y)
\end{eqnarray*}


What the error in writing this equation by latex?

the oregenal equation

• please always post a complete small document that produces the error and show the error you got. eqnarray should have more than one row, and each row should have two & but not doing that does not generate an error, just bad output. – David Carlisle Mar 8 at 21:00
• @Mico... Actually for Greeks the typo is inside \lambda and not the opposite... So, it is a bug in the name... But you are right. – koleygr Mar 8 at 21:28
• @Mico also it's a typo added since I posted my answer, otherwise the error I showed would be different, I'll revert :( – David Carlisle Mar 8 at 21:48

\documentclass{article}

\begin{document}
\begin{eqnarray*}
f(q x+(1−\lambda)y)\leq \lambda f(x)+(1−\lambda)f(y)
\end{eqnarray*}
\end{document}


produces the error

! Package inputenc Error: Unicode character − (U+2212)
(inputenc)                not set up for use with LaTeX.

See the inputenc package documentation for explanation.
Type  H <return>  for immediate help.
...

l.5 f(q x+(1−
\lambda)y)\leq \lambda f(x)+(1−\lambda)f(y)
?


use an ascii minus sign - not −

Also you should use $...$ not eqnarray* for a single line equation with no alignment points.

• thanks a lot it run with me ...............................................................................................................thanks – blue-F Mar 8 at 21:20
• @HM If this response answers your question, could you accept it? (Press the green checkbox next to the voting buttons to do that.) – bradrn Mar 9 at 1:23