1. The question is What is the slope of the line tangent to f(x)=2x^2-x-7 at x=-1 2. Must be solved using derivatives 3. So basically i know the equation (f(x+deltax)-f(x)/deltax) So i plug in the problem and i get (2(x+deltax)^2-(x+deltax)-7)-(2x^2-x-7) Now i know what the answer is to the next step (2(x^2+2xdeltax+deltax^2)-(x+deltax)-7)-(2x^2-x-7) but i do not understand this step. I only have the answer because this problem is from a video, i just have no clue how they got there. I also do not know how to do the steps after. If someone can explain the algebra they used to do these steps (be very detailed) i will be very happy.