Write a possible exponential function in $y=a·b^x$ form for each graph described below.

1. Has a $y$-intercept of $(0,3)$ and passes through the point $(2,48)$.

   Hint (a):

   Substitute the coordinates of each of the given points into the general equation $y=ab^x$.
   This creates a system of equations that can be solved for $a$ and $b$.

   More help (a):

   Substitute the values $0$ for $x$ and $3$ for $y$, then solve for $a$.

2. Passes through the points $(0,2)$ and $(3,0.25)$.

   Hint (b):

   Create two equations substituting the coordinates of the points into the equation $y=ab^x$.

   Step (b):

   Solve the system of equations for $a$ and $b$.

   More help (b):

   Be sure you use your results for $a$ and $b$ to write the equation.

   Answer (b):

   $y = 2 \cdot \left(\frac{1}{2}\right)^{x}$