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Help with tangent problem

b) At the point R, the tangent to f(x) = 1/(4x) is parrallel to the line x+4y+12=0.

Find the two possible coordinates of R.

I found the equation of the tangent to f(x) = 1/(4x), x+16y-4=0, can someone tell me what I need to do now?

Reply 1

MartyO

The parrallel line has gradient

-\frac{1}{4}

. From there, you have to derive

f(x)

and find the x-coordinates for which the slope of the tangent line to the curve is equal to

-\frac{1}{4}

Reply 2

B_9710

Original post by ℓove

The question is trying to trick you by putting the equation of a line in there. The question basically reads find the coordinates of the points on the curve