A(n)=ar^(n-1) and we can find the rate upon using the ratio of two points...
50/1250=1250r^2/1250r^0
1/25=r^2
r=1/5 so
a(n)=1250(1/5)^1=250
...
You could have also found the geometric mean which is actually quite efficient too...
The geometric mean is equal to the product of a set of elements raised to the 1/n the power where n is the number of multiplicands...in this case:
gm=(1250*50)^(1/2)=250
It’s 3n-4
I might be right or wrong
Plug in 0 for x
2*2 + (0) - 4
4 + (0) -4
0
y intercept is 0