how to plot using matlab

exp(-ax+bx^2) where x ranges from 5-250 incrementing by 1.

a and b are constants.

I was getting an error while plotting dont know what was wrong.

[Walter Roberson]

duplicates http://www.mathworks.co.uk/matlabcentral/answers/64605-how-to-plot-a-function-like-this-in-matlab