Explanation:
To find out y intercept of any function, we plug in 0 for x and solve for y
For any function y=ab^x + c
The horizontal asymptote at y=c
Now we check each function
![f(x)= 7^x -4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/z3b0j5q9m2pah35141hxzp5f58pkph191z.png)
Plug in 0 for x to find y intercept
![f(0) = 7^0 -4 = 1 -4 = -3](https://img.qammunity.org/2020/formulas/mathematics/middle-school/7k8fzohj597usa3s2560zuf222c5bba7jf.png)
y intercept at (0,-3)
Horizontal asymptote at y=c , here c= -4
So horizontal asymptote at y = -4 and y intercept at (0,-3)
![f(x)= 3^(x+2) +4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xxiyke1jn499weeyi0o70ffy722g6jnzap.png)
Plug in 0 for x to find y intercept
![f(0) = 3^(0+2)+4 = 9+4= 13](https://img.qammunity.org/2020/formulas/mathematics/middle-school/pp2miaf1eyyzweztztkeq2wb98iudo6kan.png)
y intercept at (0,13)
Horizontal asymptote at y=c , here c= 4
So horizontal asymptote at y = 4 and y intercept at (0,13)
![f(x)= 9^(x+1) -4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/3oqewyy25haswty9bbrv43oossw6ov4e1f.png)
Plug in 0 for x to find y intercept
![f(0) = 9^(0+1)-4 = 9-4= 5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/pjbe0mxrtluqrtnydq6mrk3w1bfo7q72i6.png)
y intercept at (0,5)
Horizontal asymptote at y=c , here c=-4
So horizontal asymptote at y = -4 and y intercept at (0,5)
![f(x)= 2^x+4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/pzcdgm7psmu3oi9oahozxoueanta282f1i.png)
Plug in 0 for x to find y intercept
![f(0)=2^0+4=5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zedoi7zatfnj3kj7alkgzve4hu5v9cuvme.png)
y intercept at (0,5)
Horizontal asymptote at y=c , here c= 4
So horizontal asymptote at y = 4 and y intercept at (0,5)