(5d - 1)(5d + 1) - (5d + 1)²=25d²-1-(25d²+10d+1)=25d²-1-25d²-10d-1=-10d-2
-10d·110-2= - 1100 - 2= - 1102
(5d - 1)(5d + 1) - (5d + 1)²=25d²-1-(25d²+10d+1)=25d²-1-25d²-10d-1=-10d-2
-10d·110-2= - 1100 - 2= - 1102