Find the slope of the line containing the point (4,0) and tangent to the graph of y=e^(-x) : I found the derivative (-e^(-x)) and substituted x=4. I got an answer of -0.018 but the answer is -0.050.. what did i do wrong? If http://texify.com/img/%5CLARGE%5C%21%5Cint_%7B0%7D%5E%7B3%7D%20%28x%5E2%20-4x%20%2B4%29dx%20.gif [Broken] is approximated by 3 inscribed rectangles of equal width on the x-axis, then the approximation is : I got the answer of 5 but it is apparently 1. I did : 1(4)+ 1(1)+(1)(0) where the width of the rectnagles is 1 and and the second values are the respective y values at x. What mistake did I make here as well?