Answer:
the third one
Step-by-step explanation:
-b to start is -(-6) which is 6
needs the plus and minus
the first expression is the whole numerator
 
        
                    
             
        
        
        
Are the decimal points supposed to be multiplication symbols?
        
                    
             
        
        
        
If the sol'ns are -9 and 9, then we can use this to form our eq'n:
(x - 9)(x + 9) = 0
x^2 - 81 = 0
so...
x^2 + z - 103 = x^2 -81
z - 103 = -81
z = -81 + 103
z = 22
        
             
        
        
        
Answer: x = 21
Step-by-step explanation:
look at the picture
 
        
             
        
        
        
The sine of 30° is  0.5 .
Angles don't have y-values, and neither do their sines.  But
IF you draw a graph of the sine function, AND the angles 
(the independent variable) are marked off on the x-axis of 
the graph, AND the value of the sine function of each angle 
(the dependent variable) is marked off on the y-axis of the 
graph, THEN the y-value corresponding to the angle of 30° 
would be displayed as 0.5 .