Positive Infinity: Positive infinity (+∞) represents an infinitely large and increasing value that a function approaches as the input values get larger in the positive direction.
Asymptote: An asymptote is a line that a graph approaches but never touches. In this case, there would be a horizontal asymptote at y=0 for k(x) = e^x as x approaches negative infinity.
Horizontal Shift: A horizontal shift occurs when we move a graph left or right along the x-axis. When shifting k(x) = e^x to approach negative infinity, it shifts towards the left direction.