2025年6月美国B卷 · 第 20 题

The functions \( f \) and \( g \) are defined by the equations shown, where a and b are integer constants, \( a<b \) and\( b<0 \). If\( y=f(x) \) and \( y=g(x) \) are graphed in the xy-plane, which of the following equations displays, as a constant or coefficient, the y-coordinate of the y-intercept of the graph of the corresponding function?

I. \( f(x)=a(4.2)^{x+b} \) 
II.  \( g(x)=a(4.2)^x+b \)