Omg please help for brainlist

1a

Step-by-step explanation:

8000*0.25=2000

2000*0.25=500

500*0.25=125

...

A, or f(x) = 8,000(1/4)^x

8,000 is our starting number since number of half lives is our x, and at x = 0, remaining amount of substance is equal to 8,000. As we can see on the graph, the number decreases by a quarter of its original value every time. Since the number is not getting bigger, we use a fraction instead of a whole number. Finally, the exponent makes sure that it’s a quarter of the product from before.

Hope this helps!

do you have the measurements?

if you was gonna solve for a, a is a   < -12