Answer:
   see below
Step-by-step explanation:
For simplifying expressions of this sort, there are four rules of exponents that come into play;
   
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I find it convenient to eliminate the fractions by adding the exponents, then rewrite any negative exponents as denominator factors.

 
        
             
        
        
        
Are you trying to combine? The answer would be 84.
 
        
             
        
        
        
Answer:
3.83333333333
Step-by-step explanation:
 
        
             
        
        
        
Because this is a positive parabola, it opens upwards, like a cup, and the vertex dictates what the minimum value of the function is.  In order to determine the vertex, I recommend completing the square.  Do that by first setting the function equal to 0 and then moving the 9 to the other side by subtraction.  So far: 

.  Now, to complete the square, take half the linear term, square it, and add that number to both sides.  Our linear term is 6.  Half of 6 is 3 and 3 squared is 9.  So add 9 to both sides. 

.  The right side reduces to 0, and the left side simplifies to the perfect square binomial we created while completing this process.  

.  Move the 0 back over and the vertex is clear now.  It is (-3, 0).  Therefore, 0 is the minimum point on your graph.  The first choice above is the one you want.
 
        
        
        
Answer:
30°
Step-by-step explanation:
∠A + ∠B + ∠C = 180
∠B = ∠A + 20
∠C = 2 * ∠B
<A + (∠A + 20) + (2 * ∠B) = 180
<A + (∠A + 20) + (2 * (∠A + 20)) = 180
<A + (∠A + 20) + 2∠A + 40 = 180
4∠A + 60 = 180
4∠A = 120
∠A = 30