Look carefully at the first pair:  (−3, 9), (−3, −5)  Note that x does not change, tho' y does.  This is how we recognize a vertical line (whose slope is undefined).  The equation of this vertical line is x = -3.
Looking at the second pair:  from (3,4) to (5,6), x increases by 2 and y by 2; thus, the slope is m = rise/run = 2/2 = 1.
Third pair:  as was the case with the first pair, x does not change here, and thus the equation of this (vertical) line is x=0 (which is the y-axis).  The slope is undefined.
 
        
             
        
        
        
Yes..it does. To be a function, all the inputs (x's) have to be different numbers...there can be no repeating x's...there can be repeating outputs (y's)...just not the x's
        
             
        
        
        
Answer:
it's the last one, the function is decreasing from x=-3 to x=-1
 
        
             
        
        
        
 
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