I'm not looking for the answer to this problem. I was just wondering if Sal has done a video for this proof? Basically, the question is: find the tangent line to the curve y=1/x and then calculate the area of the triangle underneath that tangent line. I have that the y-intercept to the tangent line is 2y and the x-intercept is 2x but I'm not sure how those values were derived aside from the fact that y=1/x is a symmetrical function. I could have sworn I saw the proof video but now I can't locate it. Any help would be appreciated.