Разложите на множители: а) 16-1/81х^4 б) 2х+х^2+2у-у^2

x^8 - y^8 = (x^4 - y^4) (x^4+y^4) = (x^2-y^2)*(x^2+y^2) (x^4 + y^4) = (x-y)(x+y) (x^2+y^2)*(x^2+y^4) a^8 - b^4 = (a^4 - b^2) (a^4 + b^2) = (a^2 - b)(a^2+b) (a^4 + b^2) a^9 - 1 = (a^3 - 1) (a^6+a^3 + 1) b^2-c^2 - b+c = (b-c)(b+c) - (b-c) = (b-c)(b+c-1) a + b - a^2 + b^2 = b^2 - a^2 + b + a = (b-a)(b+a) + 1(b+a) = (b-a+1)(a+b)