1. (2a+1)(3a+5)=2a×3a+2a×5+1×3a+1×5=6a²+10a+3a+5=6a²+13a+5 (4a-3)(2a-5)=8a²-26a+15 (6-2a)(-3-4a)=8a²-18a-18 (4x²-1)(2x+3)=8x³+12x²-2x-3 (-2x+5)(3x-4)=-6x²+23x-20 (-2x-3)(-4x-8)=8x²-28x+24 2.(a-3)(2a+6)-2a²+18=2a²+6a-6a-18-2a²+18=0 4a²-15-(4a-6)(2a+3)=4a²-15-(8a²+12a-12a-18)=4a²-15-8a²+18=3-4a² (a+3)(a-5)-(a-7)(a+6)=a²-5a+3a-15-(a²+6a-7a-42)=a²-2a-15-a²+a+42= =-a-15+42=27-a