is that meant to read in any case get what would be by substituting in then get of the original and then use the equation of a line formula [TEX]y-y_1=m(x-x_1) where . Hope this helps.
I presume you can do the derivative of 5e^x. To differentiate u= (x^2+ x- 1)^{-x} take the logarithm, ln(u)= -x ln(x^2+ x- 1) and differentiate both sides with respect to x.