x= -4
Step-by-step explanation:
 
        
             
        
        
        
Answer:
   decreasing at 390 miles per hour
Step-by-step explanation:
Airplane A's distance in miles to the airport can be written as ...
   a = 30 -250t . . . . . where t is in hours
Likewise, airplane B's distance to the airport can be written as ...
   b = 40 -300t
The distance (d) between the airplanes can be found using the Pythagorean theorem:
   d^2 = a^2 + b^2
Differentiating with respect to time, we have ...
   2d·d' = 2a·a' +2b·b'
   d' = (a·a' +b·b')/d
__
To find a numerical value of this, we need to find the values of its variables at t=0.
   a = 30 -250·0 = 30
   a' = -250
   b = 40 -300·0 = 40
   b' = -300
   d = √(a²+b²) = √(900+1600) = 50
Then ...
   d' = (30(-250) +40(-300))/50 = -19500/50 = -390
The distance between the airplanes is decreasing at 390 miles per hour.
 
        
             
        
        
        
X= -5 ,y=10  : Z = 1.5
X= -6 ,y=2  : Z = -2.6 (goes on forever so put the line over the 6) 
X= 6 ,y=2 : Z = 2.6 (again goes on forever so put the line over the 6)
 
        
             
        
        
        
Step-by-step explanation:
You use the I = PRN formula
P = 11 500
R = 7.25% but you have to 7.25 divide by 100 so it becomes a decimal so it should be 0.0725
N = 2 years and 6 months. This can be 2.5 years because half of 12 is 6 
the solution is 11 500 × 0.0725 × 2.5 = 2084.38