Question 714966
[4y-[5z+1)][4y+(5z+1)]


use the identity (a+b)(a-b)= a^2-b^2

a= 4y
b=(5z+1)

(4y)^2-(5z+1)^2

16y^2-(25z^2+10z+1)

16y^2-25z^2-10z-1