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Mathematics 20 Online
OpenStudy (saifoo.khan):

tangents!! tangents!! @Mathematics

OpenStudy (saifoo.khan):

OpenStudy (anonymous):

\[f(x)=\frac{-8x}{(x^2+1)}\]The derivative of this function at the point (0,0) will be the slope of the tangent line,m, at this point. We have:\[f'(x)=\frac{-8(x^2+1)+16x^2}{(x^2+1)^2}=\frac{8x^2-8}{(x^2+1)^2}\]At x=0 we get:\[f'(0)=-8\]So an equation of the tangent line at (0,0) in point-slope form is: \[y-0=-8(x-0)\]Or,\[y=-8x\]

OpenStudy (saifoo.khan):

a is correct.

OpenStudy (anonymous):

At (1,-4) we have:\[f'(1)=0\]So we have a horizontal tangent here, the equation of which is:\[y-1=0(x+1)\]Or,\[y=1\]

OpenStudy (saifoo.khan):

b is incorrect.

OpenStudy (anonymous):

Not seeing my error...

OpenStudy (saifoo.khan):

then?

OpenStudy (anonymous):

lol I see it: y+4=0(x-1) y=-4

OpenStudy (anonymous):

ooops lol

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