(7 + 5) x 6 + 3. (7 + 5 = 12, 12 x 6 = 72, 72 + 3 = 75.)
        
             
        
        
        
Answer:
P(x)=(x-2)(x-4)(x+3)(x+6)
Step-by-step explanation:
Given: P(x)=x⁴+3x³-28x²-36x+144
It is a polynomial with degree 4. 
It should maximum four factor. 
Hit and trial error method. 
Put x = 2 into P(x) 
P(2)=2⁴+3×2³-28×2²-36×2+144
P(2) = 0
So, x-2 would be factor of P(x) 
Now divide x⁴+3x³-28x²-36x+144 by x-2 to get another factors 


Put x = 4 
 
 
now divide  by x-4
 by x-4


Now factor 
 
 
 
 
Complete factor of P(x) 
P(x)=(x-2)(x-4)(x+3)(x+6)
 
        
             
        
        
        
Answer:
It takes the Dolphin 2 hours for swimming 40 miles. The penguin takes 8 hours and the swordfish will take 2/3 of an hour, which is 40 minutes to travel 40 miles.
Step-by-step explanation:
Given :
The bottlenose dolphin travels 40 miles in 2 hours. Or it takes 20 miles in 1 hour. 
Now, dividing the distance by unit rate given in the question:
40/20=2 hours
40/5=8 hours
40÷60= 2/3 hour 
Therefore, 
- the dolphin takes 2 hours for swimming 40 miles.
- the penguin takes 8 hours
- the swordfish takes 2/3 rd of an hour