wykonaj działania a) 5ab-(12a-7b-9ab)-(-4b+3a)= b)3[2x(x-4b]+12b-4x^2+8bx= c)6(z-3y)-3(-2y+7z+4x)= d)(9y+2x)(-x+y)=

a).5ab-(12a-7b-9ab)-(-4b+3a) = 5ab-12a+7b+9ab+4b-3a = -15a+14ab+11b b).3[2x(x-4b)]+12b-4x²+8bx = 3[2x²-8bx]+12b-4x²+8bx =    = 6x²-24bx+12b-4x²+8bx = 2x²+12b-16bx c).6(z-3y)-3(-2y+7z+4x) = 6z-18y+6y-21z-12x = -12x-12y-15z d).(9y+2x)(-x+y) = -9xy+9y²-2x²+2xy = -2x²-7xy+9y²