Approximate the slope of a tangent line

Question

Approximate the slope of the line tangent to the graph of f(x) = xcosx at x = -1

Answer 1

Downvoted, probably, because the APPROXIMATE directive means use the "slope of secant" idea, using two points very close together, say x=-1 and x=-0.999

 

That's just a little bit of computing work, for you to do. Calculus books have examples. (Remember when they were taking the limit of the Difference Quotient?)