a) (c-2)*(c+3)= c^2+3c-2c-6=c^2+c-6
б) (c-1)*(c+4)-c^2=c^2+4c-c-4-c^2=3c-4
в) 16x*(3-4x)=48x-64x^2
г)4x*(x+5)-(2x+5)^2= 4x^2+20x-(4x^2+10x+10x+25)= 4x^2+20x-4x^2-20x-25=-25
д) -3x(2-x)+(3x+1)(x-2)= -6x+3x^2+3x^2-6x+x-2= -11x+6x^2-2
е) 3(2x-1)^2+12x=3*(4x^2-8x+1)+12x=12x^2-24x+3+12x=12x^2-12x+3
ж)(2-x)*(2+x)*(x-1)+x^2*(x-1)=(4-x^2)*(x-1)+x^3-x^2=4x-4-x^3+x^2+x^3-x^2=4x-4
з) 7x*(x-y)-3y(x+y)-2x(2x-3y)=7x^2-7xy-3xy-3y^2-4x^2+6xy=-4x^2-4xy-3y^2
и) (a+6)^2-2a*(3-2a)=a^2+6a+6a+36-6a+4a^2=5a^2+6a+36