What is the equation of the tangent line of $f (x) = \frac{1}{1 + 2 x^{2}}$ $f(x) =1/ (1+2x^2)$ at $x = 3$ $x = 3$ ?

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Answer 1 · 2016-05-15T21:03:47

$y = - \frac{12}{361} \cdot x + \frac{45}{361}$ $y=-12/361*x+45/361$
First derivation and $f (3) = \frac{1}{19}$ $f(3)=1/19$

This is quite easy with the first derivation.

What is the equation of the tangent line of f(x)=11+2x2f(x) =1/ (1+2x^2) at x=3 x = 3?