#### Topic: Cannot derive a formula or draw multiple tangents

I am measuring how the gradient changes the smoothness of a curve (e.g. measure of learning curve based on grades at school) and, I am trying to do this graphically, however, I am not allowed to use more than one tangent, why is this a limitation?

f(x) = x^2 + x + 3x^2

dy/dx = ? Is this possible?

It would be useful if I could export information to a CSV file and to a picture file e.g. jpeg/png.

Function > Insert function (Ins) is available.

Function > Insert tangent/normal is disabled after I have drawn the tangent, so I cannot take further measures.

I would suggest using Microsoft mathematics as a benchmark tool.

Attachments are not always allowed for upload to this forum but is there a list of acceptable file types documented and what do the error messages read are they specific or vague? Or is this a bug?