Answer:
Tn = 64-4n
Step-by-step explanation:
The nth term of an AP is expressed as:
Tn = a+(n-1)d
a is the common difference
n is the number of terms
d is the common difference
Given the 6th term a6 = 40
T6 = a+(6-1)d
T6 = a+5d
40 = a+5d ... (1)
Given the 20th term a20 = -16
T20 = a+(20-1)d
T20 = a+19d
-16 = a+19d... (2)
Solving both equation simultaneously
40 = a+5d
-16 = a+19d
Subtracting both equation
40-(-16) = 5d-19d
56 = -14d
d = 56/-14
d = -4
Substituting d = -4 into equation 
a+5d = 40
a+5(-4) = 40
a-20 = 40
a = 20+40
a = 60
Given a = 60, d = -4, to get the nth term of the sequence:
Tn = a+(n-1)d
Tn = 60+(n-1)(-4)
Tn = 60+(-4n+4)
Tn = 60-4n+4
Tn = 64-4n
 
        
             
        
        
        
Chelsea vs. Atlético Madrid, Champions League: Confirmed lineups; how to watch
        
             
        
        
        
-2a from both sides then divide by -5 and a=1
        
                    
             
        
        
        
Please provide a correct formula of your polynomial. 
Where are the signs of (4x^2) and (3x)???
        
             
        
        
        
I highly recommend you use photomath for this. but i have the answer! 
26-16x is the answer