A² - b² + 2(a+b)² = (a+b)(a-b) + (a+b) * 2(a+b) = (a+b) (a-b +2(a+b)) =
=(a+b)(a - b +2a +2b) = (a+b)(3a - b)
b² - c² - 10(b-c)² = (b-c)(b+c) - (b-c)*10(b-c) = (b-c)(b +c -10(b-c))=
= (b -c)(b + c - 10b + 10c) = (b-c)( -9b + 11c)
2(x - y)² + 3x² - 3y² =2(x-y)(x-y) +3(x² - y²) = (x-y) * 2(x-y) + (x-y) * 3(x+y)=
= (x-y)(2(x-y) +3(x+y) ) = (x-y)(2x -2y +3x+3y) = (x-y)(5x +y)
5a² - 5 - 4(a+1)² = 5(a² - 1) - 4(a+1)(a+1) = 5(a-1)(a+1) - 4(a+1)(a+1)=
= (a+1)(5(a-1) - 4(a+1))= (a+1)(5a-5 -4a-4) =(a+1)(a - 9)