Is it an inverse function
        
             
        
        
        
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<em>Correction to your question text: diameter, not radius.</em>
The area of a circle is given by:

The radius is half of the diameter.

Substitute and solve.

 
        
             
        
        
        
Answer:
2x + 4 = 10 = x =3
Step-by-step explanation:
09 - 31 = 0  (the variable x is not present in the given system)
0 +5=6  (the variable x is not present in the given system)
2x + 4 = 10  = x = 3
09-1=4  (the variable x is not present in the given system)
51 - 7 = 1  (the variable x is not present in the given system)
3x + 1 = 9 = x = 8/3
 
        
             
        
        
        
Answer:
Step-by-step explanation:
Take the square root of 5, which is 2.236, aka not a rational number. It doesn't come out to a whole number so therefore there is no rational solution 
 
        
             
        
        
        
Answer:
   33
Step-by-step explanation:
3 years ago, the difference in ages was twice Daniel's age. So, Daniel was 20/2 = 10 years old at that time. Ben was 30.
Now, Ben is 33.
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If two numbers have a ratio of 3:1, their difference is (3-1) = 2 times the smaller number.