Answer:
the amount of time it takes for approximately 50% of a radioactive atom sample to undergo nuclear decay
 
        
             
        
        
        
Answer:
B = 50°
D = 40°
A = 90°
C = A = 90°
Step-by-step explanation:
I hope that it's a correct answers. 
 
        
             
        
        
        
Answer:

Step-by-step explanation:
Combining like terms:


 
        
                    
             
        
        
        
Answer:
  ={6,7,8,9,10}.
={6,7,8,9,10}.
Step-by-step explanation:
We have an empty set: M={} and the set N={6,7,8,9,10}.
The union of these two sets are elements in M or N or both.
Since the M is a null set, 
Therefore:  ={6,7,8,9,10}.
={6,7,8,9,10}.
The union for the given sets is {6,7,8,9,10}.