Answer:
C) 
Step-by-step explanation:
By the cos double angle formula, we know  Substituting
 Substituting  into the formula, we get
 into the formula, we get
 .
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The answer is C.
  
        
             
        
        
        
Answer:
The value of x is -3. 
Step-by-step explanation:
To find x, we have to put everything in base 6 and continue to simplify. Since we know that 216 is 6^3, we can replace that. 
6^x = 1/216
6^x = 1/(6^3)
Now, when there is a power in the denominator, we know we can move it to the numerator by making it negative. We can do that to get the bases to match. 
6^x = 1/(6^3)
6^x = 6^-3
Now that they are both put in simple base 6 systems, we can just eliminate the bases and assume that the powers are equal. This lets us know that x = -3. 
 
        
             
        
        
        
Where are the quadratic equations?
        
             
        
        
        
23 x 5% = 
23 x 0.05= 1.15 (total sales tax)
23 + 1.15= $24.15 (total price)