(1)①原式=-27x3y6•x6y2 =-x9y8;
②原式=-a6x5y3+(-a5xy2) =ax4y;
(2)①原式=(x2+y2-2xy)-1=(x-y)2-1 =(x-y+1)(x-y-1);
②原式=(a-b)(3a+b)2-(a+3b)2(a-b) =(a-b)[(3a+b)2-(a+3b)2] =(a-b)[(3a+b)+(a+3b)][(3a+b)-(a+3b)] =(a-b)(4a+4b)(2a-2b) =8(a-b)2(a+b).
(3)化简得:16x-7=41, 即16x=48 则x=3. |