\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}
