dcowboys107 Posted August 18, 2010 Share Posted August 18, 2010 Write equations for the two straight lines that pass through the poing (2,5) and are tangent to the parabola y=4x-x^2. I drew the figure and the lines. I fought the slope for the tangent lines (2 and -2) and eventually the equations y=-2x+9 and y=2x+1 When I plugged the three equations into my calcuator to see if I was right it seems that I was off on y=-2x+9, that it doesn't reach 5 when x is two but at 4. The second one seems right. Am I right and the calcultar be wrong? Thanks. Link to comment Share on other sites More sharing options...
DJBruce Posted August 18, 2010 Share Posted August 18, 2010 Did you try checking your math by hand? Link to comment Share on other sites More sharing options...
dcowboys107 Posted August 19, 2010 Author Share Posted August 19, 2010 I think I got it to work. Does that seem like the right answer though? Link to comment Share on other sites More sharing options...
DJBruce Posted August 19, 2010 Share Posted August 19, 2010 It looks like it, and when I checked it by hand and calculator it seemed to work. So I am assuming you must have just entered something improperly into your calculator. (Ergo why I asked you to check it manually.) Link to comment Share on other sites More sharing options...
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