а) (a+b)(a-2b) + (2b-a)(2b+a) = a^2 - 2ab + ab - 2b^2 + 4b^2 - 2ab - 2ab - a^= a^2 - 2ab + ab - 2b^2 + 4b^2 - 2ab - 2ab - a^= 4b^2 - 2ab - 2ab + ab + a^2 - a^= 4b^2 - 4ab + ab
б) (3x + 2)^2 - (3x - 1)^2 = 9x^2 + 12x + 4 - (9x^2 - 6x + 1= 9x^2 + 12x + 4 - 9x^2 + 6x - = 12x + 4 + 6x - = 18x + 3
а) (a+b)(a-2b) + (2b-a)(2b+a) = a^2 - 2ab + ab - 2b^2 + 4b^2 - 2ab - 2ab - a^
= a^2 - 2ab + ab - 2b^2 + 4b^2 - 2ab - 2ab - a^
= 4b^2 - 2ab - 2ab + ab + a^2 - a^
= 4b^2 - 4ab + ab
б) (3x + 2)^2 - (3x - 1)^2 = 9x^2 + 12x + 4 - (9x^2 - 6x + 1
= 9x^2 + 12x + 4 - 9x^2 + 6x -
= 12x + 4 + 6x -
= 18x + 3