Помогитее!!!! упростите: (7-2х-х^2)-(х-2)(х+3) (3m^2+3n^2)-(2m+n)(m+2n) (n+1)(2n-3)+(n-1)(3n+1) (x-y)(2x-3y)-(3x-y)(2x+y)

[latex](7-2x- x^{2} )-(x-2)(x+3) = 7 - 2x - x^{2} - x^{2} - 3x + 2x +6 [/latex] = = [latex]-2 x^{2} -3x + 11[/latex] [latex](3m^2+3n^2)-(2m+n)(m+2n) = 3m^2 + 3n^2 - 2m^2 - 4mn -nm - \\ -2n^2 = n^2 + m^2 - 5mn \\[/latex] [latex](n+1)(2n-3)+(n-1)(3n+1) = 2n^2 -3n +2n -3 +3n^2+n-3n[/latex] [latex]-1 = 5n^2 -3n -3[/latex]   [latex](x-y)(2x-3y)-(3x-y)(2x+y) = 2x^2-3xy-2xy+3y^2-6x^2[/latex][latex]-3xy+2xy+y^2 = 4y^2 - 4x^2 -6xy[/latex].