Answer:
Given equation: 
when we complete the square , we take half of the value of 8 , then square it, and added to the left sides, we get;
∵8 is the value 
Notice that, we add this both sides so that it maintains the equality.
then;
[ 
]
Simplify:
The number must be added to complete the square is, 
2) 5.625 mg will be left
Explanation:
1) Half-life = 17.5 days
initial amount of Arsenic-74 = 90 mg
To get the equation, we will use the equation of half-life:
2) we need to find the remaining amount of Arsenic-74 after 70 days
t = 70
So after 70 days, 5.625 mg will be left
14 + 8(12-34)
14 + 8(-22)
14 - 176
- 162 is your answer
hope this helps
The answer is negative 80 or like this -80
