Answer:
(5x - 4) • (x + 4)
Explanation:
Multiply the coefficient of the first term by the constant 5 • -16 = -80
Find two factors of -80 whose sum equals the coefficient of the middle term, which is 16 .
Rewrite the polynomial splitting the middle term using the two factors found in step 2 above, -4 and 20
5x2 - 4x + 20x - 16
Add up the first 2 terms, pulling out like factors :
x • (5x-4)
Add up the last 2 terms, pulling out common factors :
4 • (5x-4)
Add up the four terms of step 4 :
(x+4) • (5x-4)
Which is the desired factorization