Answer
We know that the graph of an exponential function $y=b^{x}$ has a y-intercept of $(0,1)$ because $y=f(0)=b^{0}=1$.
Work Step by Step
The graph of an exponential function $y=b^{x}$ has a y-intercept of $(0,1)$ because $y=f(0)=b^{0}=1$. In other words, the exponential function contains this point, because the value of a nonzero real number $b$ raised to the power of 0 is equal to 1. Therefore, the graph of an exponential function $y=b^{x}$ crosses the y-axis at a value of $y=1$.