单项式的乘法
问题描述：
单项式的乘法
1.(X+2)(X-2) 2.(3X-1)(2X+1) 3.(X-3Y)(X+7Y) 4.(2X+5Y)(3X-2Y)
答
1.(X+2)(X-2)
=X^2-2X+2X-4
=X^2-4
2.(3X-1)(2X+1)
=6X^2+3X-2X-1
=6X^2+X-1
3.(X-3Y)(X+7Y)
=X^2+7XY-3XY-21Y^2
=X^2+4XY-21Y^2
4.(2X+5Y)(3X-2Y)
=6X^2-4XY+15XY-10Y^2
=6X^2+11XY-10Y^2