Выражение (x-3)^2-8 12x-(x+6)^2 (x-5)^2-x(x+3) (6a-b)^2-(9a-b)(4a+2b)

1. (x-3)^2-8=x^2-6x+9-8=x^2-6x+1
2. 12x-(x+6)^2=12x-(x^2+12x+36)=12x-x^2-12x-36=-x^2-36=-(x^2+36)=-(x-6)(x+6)
3. (x-5)^2-x(x+3)=x^2-10x+25-x^2-3x=-13x+25
4. (6a-b)^2-(9a-b)(4a+2b)=36a^2-12ab+b^2-36a^2-18ab+4ab+2b^2=-26ab+3b^2=3b^2-26ab=b(3b-26a)