what information can be derived from the color of a star

The tempreature of a star, because the hottest stars are blue, and it goes through the colors to red stars being the coolest.

See diagram.we use washers to get the area and we will be integrating with respect to xouter radius is the  distance between y = e^x and y = -1    inner radius of washer is the distance between y = 1 and y = -1    the area of one cross-section of a washer is    solid lies between x = 0 and x = 2. the volume is    if you need this expanded, then    the question doesn't say to evaluate, so we're done.   

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.