(b+3)² = b²+2*b*3+3² = b²+6b+9
25b²+10b+1 = (5b)²+2*5b*1+1² = (5b+1)²
(2a-3b)(3b+2a) = (2a-3b)(2a+3b) = (2a)²-(3b)² = 4a²-9b²
1+b³ = 1³+b³ = (1+b)(1²-1*b+b²) = (1+b)(1-b+b²)
(10-c)² = 10²-2*10*c+c² = 100-20c+c²
81a²-18ab+b² = (9a)²-2*9a*b+b² = (9a-b)²
-49a²+16b² = 16b²-49a² = (4b)²-(7a)² = (4b-7a)(4b+7a)
(-3-b)² = (-(3+b))² = (3+b)² = 3²+2*3*b+b² = 9+6b+b²