Hi i wonder what the wrong is in my calculation is :
deside the tangent and the normal to the curve f(x) = ln(x + sqrt(1 + x^2) in the pont (0,0).
f´(x)= 1/(sqrt(x^2 + 1))
f´(0) = 1/(sqrt(0^2 + 1)) = 1
y = kx + m, y = 0, x = 0, k = 1
m = y -kx = 1 - 1 * 0 = 0
but I must have done wrong somewere, for the right answer is tangen, y= x, and the normal, y = -x.
help someone :/