a) 3a^2 -6ab+3b^2 b) x^2-y^2 -5×(x-y) c) 4- x^2 +2xy-y^2 d) x^2 + x -6 e) 18 a^3 b^2 – 9a^2 b^3 f)x^2-y^2-7x-7y g)16-x^2-2xy-y^2 h)x^2-5x+6 Giúp mik

$\begin{array}{l}a)\,\,3a^2 – 6ab + 3b^2\\=3(a^2 – 2ab +b^2)\\=3(a – b)^2\\b)\,\,x^2 – y^2 – 5(x – y)\\=(x-y)(x+y) – 5(x – y)\\= (x -y)(x +y-5)\\c)\,\,4 – x^2 + 2xy – y^2\\=2^2 – (x^2 – 2xy + y^2)\\=2^2 – (x – y)^2\\=(2 – x + y )(2 + x – y)\\d)\,\,x^2 + x – 6\\=x^2 – 2x + 3x – 6\\=x(x -2)+3(x -2)\\=(x-2)(x+3)\\e)\,\,18a^3b^2 – 9a^2b^3\\=9a^2b^2.2a – 9a^2b^2.b\\=9a^2b^2(2a – b)\\f)\,\,x^2 – y^2- 7x – 7y\\=(x – y)(x + y) – 7(x + y)\\= (x + y)(x – y – 7)\\g)\,\,16 – x^2 – 2xy – y^2\\=4^2 – (x^2 + 2xy + y^2)\\=4^2 – (x + y)^2\\=(4- x – y)(4+x+y)\\h)\,\,x^2 – 5x + 6\\=x^2 – 3x – 2x + 6\\= x(x -3) – 2(x -3)\\= (x -3)(x-2)\end{array}$