Answer:
y= 250( 1-0.21)^x
Step-by-step explanation:
This represents exponential decay
Answer:
Use the Quadratic formula
It is related to econometrics, however using simple algebraic logic we can solve this problem. General formula with residual is

, where r is a residual. Plugging the pair into the formula, we obtain that

and r=0.5
Answer ; -1/2
when expanded
5-8a-2+3a=13
5a=3-13
a=-5/10
a= -1/2