Answer to Question #48136 in Calculus for Lanaye

Dear Lanaye. Are you sure that your question is correct? Function y=bx is not exponential, it is a linear function.
Maybe you meant y=e^bx which is an exponential function. The y-intercept is a point where the graph of function crosses the y-axis, in other words, it is a point on the graph where x is zero. For y=bx, the y-intercept is (0,0), because y(0)=b*0=0. For y=e^bx, the y-intercept is (0,1), because y(0)=e^b*0=e⁰=1.