F futuredoc_christie Guest Mar 21, 2009 #1 I thought d/dx(arctanx) = 1/(1+x^2), so when you square a square root, the inside comes out, so it would be 1/(1+7x^2-1) = 1/7x^2, but it's telling me that's the wrong answer... so what am I doing wrong?
I thought d/dx(arctanx) = 1/(1+x^2), so when you square a square root, the inside comes out, so it would be 1/(1+7x^2-1) = 1/7x^2, but it's telling me that's the wrong answer... so what am I doing wrong?
