1) (a²+3ab-b²)·ab 2) abc·(2a²b-3abc) 3) (a-b+c) (a-c) > 4) (a²-b²) (a+b) 5) (a-3) (a-2)-(a-1) (a-4)

1) [latex]( a^{2} +3ab- b^{2})ab= a^{3}b+3 a^{2} b^{2} -a b^{3} [/latex]2) [latex]abc(2 a^{2}b-2abc)=2 a^{3} b^{2}c-3a^{2} b^{2} c^{2} [/latex]3) [latex](a-b+c)(a-c)= a^{2}-ac-ab+bc+ac- c^{2} = a^{2}-ab+bc- c^{2} [/latex]4) [latex]( a^{2} - b^{2})(a+b)= a^{3} + a^{2} b-a b^{2} - b^{3} [/latex]5) [latex](a-3)(a-2)-(a-1)(a-4)= a^{2} -5a+6- a^{2} +5a-4=2[/latex]