The answer is 6n^3+n^2+6n-4 I hope I helped you!
        
                    
             
        
        
        
Step-by-step explanation:
AO = DO
2x+3 = 5x
3 = 5x-2x
3 = 3x
x = 1
DO = 5(1)=5cm
AC = 2×5 = 10cm
BC =√10²-8²
 = √100-64
 =√36
 =6 cm
therefore, the perimeter of the rectangle
= 2×(8+6) = 2(14) = 28 cm
 
        
             
        
        
        
Step-by-step explanation:
use formula of length of the diagonal of rectangle equal to d/rt2
 
        
             
        
        
        
Answer:
There the buoy is 17.3 m from the place where the diver started.
Step-by-step explanation:
a² + b² =c²
⇒ 10² + b² = 20²
⇒ 100 + b² = 400
⇒ b² = 400 - 100
⇒ b²= 300
⇒ b = 
⇒ b = 17.3 m
There the buoy is 17.3 m from the place where the diver started.