(1)(a+2b)(a-b)=______;
(2)(3a-2)(2a+5)=______;
(3)(x-3)(3x-4)=______;
(4)(3x-y)(x+2y)=______.
网友回答
解:(1)(a+2b)(a-b)=a2-ab+2ab-2b2=a2+ab-2b2;
(2)(3a-2)(2a+5)=6a2+15a-4a-10=6a2+11a-10;
(3)(x-3)(3x-4)=3x2-4x-9x+12=3x2-13x+12;
(4)(3x-y)(x+2y)=3x2+6xy-xy-2y2=3x2+5xy-2y2.
故