Hi ya all! I'm having difficulties with estimating the temperature of the surface of the sun from a given solar spectrum. I've already determined the photon energy of the most common photons (1.15 eV). I also know that the curve of the solar spectrum (photon energy on the x-axis and intensity on the y-axis) is described with (hf^3)/((e^(hf/Kb T))-1) where the frequency f corresponding to 1 eV energy is 2.417970 x 10^14 Hz. Now the way to retrieve the correct answer is the following: 1) Differentiate the formula. 2) Calculate the frequency of the most common photons and fill that in the formula. 3) Solve the equation where the differentiated formula (with f filled in) is set zero. (This may be done with a graphic calculator) The only problem is that I don't seem to differentiate the formula correctly, because my calculator just can't find the points where it's zero. Could someone pleaaaaaaaaaaaaaaaaase help me to differentiate it the right way?