Answer:
(x+1) • (x-5)
Explanation:
The first term is, x2 its coefficient is 1 . 
The middle term is, -4x its coefficient is -4 . 
The last term, "the constant", is -5 
 
Step-1 : Multiply the coefficient of the first term by the constant 1 • -5 = -5 
 
Step-2 : Find two factors of -5 whose sum equals the coefficient of the middle term, which is -4 . 
 
 -5 + 1 = -4 That's it 
 
Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above, -5 and 1 
 x2 - 5x + 1x - 5 
 
Step-4 : Add up the first 2 terms, pulling out like factors : 
 x • (x-5) 
 Add up the last 2 terms, pulling out common factors : 
 1 • (x-5) 
Step-5 : Add up the four terms of step 4 : 
 (x+1) • (x-5)