Answer:A
Step-by-step explanation:
<span> half life i= 78 hours
amount after 78 hours is 395 kg:
395 = 790e^(k*78)
Dividing by 790 and taking natural log
ln (395/790) = (k*78)
-0.6931 = 78k
-0.00888 = k
lets calculate how much is left after 18 hours:
Amount(18)
= 790e^(-0.00888*18)
Amount = 673.301 kg
hope this helps</span>
7- 5n=6+6(n+2)
7- 5n=6+6n+12
7 -5n=18+6n
5n-6n=18-7
-11n=11
n=-1
ANSWER

EXPLANATION
The quadratic equation is:

Group variable terms:

Add the square of half, the coefficient of y to both sides.


The LHS us now a perfect square trinomial:

Take square root:


The first choice is correct.
Answer:
1
Step-by-step explanation:
2/7+5/7=7/7=1 because 7/7 would be a 1 whole