Originally Posted by
ohmygodshoes alright...im trying to find the tangent line of
f(x) = ln(x) at x = 4
so i know that the slope simply equals f`(x) which is
f`(x) = 1/x = 1/4 = m
then i use that in the equation of a tangent line,
y = mx + b
then i use the values of x and y from f(x) = ln(x) and i get
f(4) = ln(4) = .4 so x = 4 , y = 1.4
then plugging these in the equation i get
1.4 = 1/4(4) + b and then this equals b = 1.4 - 1 = .4 so b = .4
now i plug all these values in and get
y = 1/4x + .4
but i got it wrong...can someone please tell me why and show me how i messed up...thanks