BB, Nerdy re? ke ho eklo paayo bhanera hepdine. :P. i m anything but nerdy...;) dunno abt TP though. :D Pat, dude, with each post you are more close to proving yourself a "smarta$$". no offence hai, malai timi bhai jasto laagera maatra bhanna khojya ho. applying one's creativity is one thing and DENYING to learn is another. I am not expecting you to be creative right away, but with the clues i have given to you so far, any peanut size brain will have deciphered it long time back. If you know anything about 'Plagiarism" then you will know what is stopping me to do the damn proof step by step. I don';t mind helping but i expect others to learn at the same time. I am gonna show you the simplest method by which it can be proved (chain rule). 1) d(ln(x))/dx=1/x (we know that and dont ask me why, do some reading) 2) ln(e^x)=x (we know that, and dont ask me why, do some reading) 3) hence d( ln(e^x)/dx=dx/dx=1 (ho ki haina?) 4) put u=e^x 5) differentiating both sides w.r.t. x on 4) du/dx=d(e^x)/dx 6) now from 3) (d (ln u)/du).du/dx=1 or, (1/u).du/dx=1 (from fact 1)) or, du/dx=u therefore d(e^x)/dx=e^x There could be other methods as well. Right now i can think of 5 different methods. I explained you the simplest one. ONE REQUEST: DOn't copy and paste what i did. Try to learn, it will ONLY help you. I love mathematics so could not stop helping you. Loote