The domain is all input values(otherwise known as all x-values on the x-axis) and the range is all possible output values( y-values, as shown on the y-axis). Functions are expressions involving 1 or more variables, in a function x-values are only allowed 1 y-value or else it isn’t considered a function. 
Hope this helps!
        
             
        
        
        
A) -11 degrees 
B) 77 degrees colder
        
                    
             
        
        
        
C. Seventh year because that’s how much he will earn from the interest
        
             
        
        
        
A complex number in the denominator is eliminated by multiplying the fraction by 1 in the form of the conjugate of that denominator divided by itself.

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A graphing or scientific calculator that handles complex numbers can do this simplification for you.