That's the correct formula for the derivative. Set x = 2, y = 1 to find the slope. Then set the derivative equal to this slope to get an equation for the unknown point(s). It will be linear, so you can solve it for x or y (you choose). The other equation is the original equation . When you eliminate one of the two unknowns, you will be left with a quadratic equation for the other one. One solution corresponds to the point (2,1) which you know already, the other one is new.Originally Posted bydizzystudent

is correct. Mathcad tells me the limit of the difference quotient is 0. Are you allowed to use L'Hopital's rule? Otherwise the only thing you can do is use .1970 -

the function is defined for all x not equal to 0, in the interval by