99^2 = (100-1)^2= 10000 - 200 + 1 = 9801
<span>202^2 = (200+2)^2 = 40000 + 800 + 4 = 400804</span>
S– a*b
P– 2*(a+b)
Вот так
(a-b)²-2b²+2a²=a²-2ab+b²-2b²+2a²=
=3a²-2ab-b²
a) (a-b)(3a+b)=3a²-2ab-b²
b)3(a-b)(2b-a)=6ab-a²-2b²
c) (a-b)(2a-b)=2a²-4ab+b²
d) (a-b)(4a+b)=4a²-3ab-b²