\begin{Schunk}
\begin{Sinput}
 x <- seq(0,10,length.out=1000)
 alpha <- c(1,2.5, 5)
 y1 <- x^(alpha[1]-1)*exp(-x)
 y2 <- x^(alpha[2]-1)*exp(-x)
 y3 <- x^(alpha[3]-1)*exp(-x)
 plot(x, y1, type="l", xlab="x", ylab=expression(paste(x^{alpha-1}*e^{-x})),  ylim=c(0,6))
 lines(x, y2, lty=2)
 lines(x, y3, lty=3)
 legend("topright",legend=c(expression(paste(alpha==1)),expression(paste(alpha==2.5)),expression(paste(alpha==5))), lty=c(1,2,3))
\end{Sinput}
\end{Schunk}
