(а+15)^2=a^2+30a+225
(3-n)^2=9-6n+n^2
(8b-0,5)^2=64b^2-8b+0,25
b^2-1=(b-1)(b+1)
25-64y^2=(5-8y)(5+8y)
81^2-71^2=(81-71)(81+71)=10*152=1520
(а+15)^2=a^2+30a+225
(3-n)^2=9-6n+n^2
(8b-0,5)^2=64b^2-8b+0,25
b^2-1=(b-1)(b+1)
25-64y^2=(5-8y)(5+8y)
81^2-71^2=(81-71)(81+71)=10*152=1520