多项式乘法,1.(3X-Y)(X+2Y) 2.-2(a-2b)(3a+b) 3.3(X-2/1)(x+3/1)4.(a-2)(a-3)-(a-1)(a-4)
问题描述：
多项式乘法,
1.(3X-Y)(X+2Y) 2.-2(a-2b)(3a+b) 3.3(X-2/1)(x+3/1)
4.(a-2)(a-3)-(a-1)(a-4)
答
1、原式=3X(X+2Y)-Y(X+2Y)=3X2+6XY-XY-2Y2=3X2-5XY-2Y2
2、原式=-2a(3a+b)+4b (3a+b)= -6a2-2ab+12ab+4b2=-6a2+10ab+4b2
3、你的X和x本来就不一样，还是你不小心打错了？
4、原式=a2-3a-2a-a2+4a+a+4=(a2-a2)+(4a+a-3a-2a)+4=4
答
1.(3X-Y)(X+2Y) =3x平方-xy+6xy-2y平方= 3x平方+5xy-2y平方 2.-2(a-2b)(3a+b) 3.3(X-2/1)(x+3/1)
4.(a-2)(a-3)-(a-1)(a-4)
答
1.(3X-Y)(X+2Y) =3x*x+6xy-xy-2y*y=3x*x+5xy-2y*y2.-2(a-2b)(3a+b)=-2(3a*a-ab+6ab-2b*b)= -6a*a-10ab+4b*b3.3(X-2/1)(x+3/1)=3(x*x+3x-2x-6)=3x*x+3x-184.(a-2)(a-3)-(a-1)(a-4)=a*a-5a+6-(a*a-5a+4)=10