Answer:
should be -8
Step-by-step explanation:
when reflecting over the x-axis, y changes from positive to negative or negative to positive. x stays the same. 
when reflecting over the y-axis, x changes from positive to negative or negative to positive. y stays the same. 
 
        
                    
             
        
        
        
Answer:
1. 1343 years
2. 9 hours
3. 39 years
Step-by-step explanation:
1. Given, half-life of carbon = 5730 years.
∴ λ = 0.693/half-life of carbon = 0.693/5730 = 0.000121 
If N₀ = 100 then N = 85 
Formula:- N = N₀*e^(-λt)
∴ 85 = 100 * e^(-0.000121t)
∴㏑(-0.85)=-0.000121t
∴ t = 1343 years
2. Given half-life of aspirin = 12 hours
λ = 0.693/12 = 0.5775 
Also N₀ = 100 then 70 will disintegrate and N = 30 will remain disintegrated.
∴ 70 = 100 *e^(-0.05775t)
0.70 = e^(-0.05775t)
㏑(0.70) = -0.05775t
∴ t = 9 hours
3.  The population of the birds as as A=A₀*e^(kt)
Given that the population of birds fell from 1400 from 1000, We are asked how much time it will take for the population to drop below 100, let that be x years.
The population is 1400 when f = 0, And it is 1000 when f = 5
We can write the following equation :
1400 = 1000e^(5t).
∴1400/1000 = e^(5k)
∴ k = ㏑(1.4)/5
We need to find x such that 1400/100 = e^(xk)
14 = e^(xk)
∴ x = 39 years
 
        
             
        
        
        
9514 1404 393
Answer:
   12 dimes
Step-by-step explanation:
Let q represent the number of quarters. Then the number of dimes is 16-q and the total value is ...
   0.25q +0.10(16 -q) = 2.20
   0.15q +1.60 = 2.20 . . . . . . . simplify
   0.15q = 0.60 . . . . . . . . subtract 1.60
   q = 4 . . . . . . . . . . . divide by 0.15
   16-q = 12
There are 12 dimes in the collection.
 
        
             
        
        
        
Answer:
36 cents
Step-by-step explanation:
 
        
             
        
        
        
Answer:
76,000,000
Step-by-step explanation:
Look at the 100,000 place and see whether to round up or down - 8 is larger than 5, therefore 75,000,000 gets rounded up to 76,000,000