Someone who finds that he has traveled to a new town and has no memory of his old life is likely suffering from
a) dissociative identity disorder.
b) dissociative fugue.
c) dissociative amnesia.
d) multiple personality disorder.

Someone who finds that he has traveled to a new town and has no memory of his old life is likely suffering from dissociative fugue. 

You need to figure out at which x-value does the graph has a tangent line slope of -1.remember, the derivative is the slope of the tangent line. so find the derivative function and set it to equal -1 to find the x-value that will have a tangent line slope of 0.differentiate with the chain rule.    set the derivative to equal -1 and solve for x.      take log base 10 of both sides. also recall that  .    so the x-coord of the point of tangency is .the y-coordinate of this point of tangency can be calculated using the original function:     using point-slope form, the equation of the tangent line is      the x-intercept of this tangent line is when the graph is at y=0.    this rounds off to  .choice c.

It is beneficial, you learn a lot watching television.