N-347
a)23x^3-14xxy+6x^3-2x^2*8y+4=23x^3+6x^3-14x^2y+3=29x^3-16x^2y+4
б)2y*y^3-3y^2*4y^2+6y^4-8y^4-11=2y^4-12y^4+6y^4-8y^4-11=-12y^4-11
в)5x*(-4x^4)-2x^2*x^3+27x^5-x^6=-20x^5-6x^5+27x^5-x^6=x^5-x^6=x^5(1-x)
г)16a*(-a^2b)+18a^3b-12aab+14a^2b=-16a^3b+18a^3b-12a^3b+14a^2b=2a^3b+2a^2b=2a^2b(a+1)