B. (k+10f)(k-5f) you can tell in 2 ways.  1. if the second sign is neg then the signs in the factors are going to be one neg and one positive so that knocks out C and D.  Then you look at the second term and since the 5 is positive then the 10 has to be positive so you end up with a positive 5kf.
The second way is to FOIL them out.  When you check B you get 

 combine your like terms and you have your original expression of 

Hope that helps
 
        
        
        
Answer:
f - 4(g^7)
It's simple algebraic operations!
 
        
             
        
        
        
1)  (-4) + (-9) = -13 
2) 5 + (-12) = -7 
3) -6 + 5 = -1 
4) -7 + 7 = 0 
<span>5)  -7 + 2 ___ 3 + (-9)
       - 5  ____    - 6 
</span>-7 + 2  >  3 + (-9)
6)  <span>4 + (-8) ___ 6 + (-8) + (-6)  
     - 4 ____    - 8 
</span><span>4 + (-8) >  6 + (-8) + (-6)
7)  </span><span>$66
8)  </span><span>-$12
</span>
        
             
        
        
        
5/10 and 2/10 beacuse tenth is the bottom number
        
                    
             
        
        
        
The vector equation of the line through the origin perpendicular to the plane is
.. (x, y, z) = t(2, 3, -1)
so the point of interest will satisfy
.. 2(2t) +3(3t) -(-t) = -3
.. 14t = -3
.. t = -3/14
and its coordinates are (x, y, z) = (-3/7, -9/14, 3/14)