2.如果(x2-y2)2+k=x4+x2y2+y4,则单项式k等于( )
| A. | -x2y2 | B. | x2y2 | C. | 2x2y2 | D. | 3x2y2 |
1.计算(a-b)(-a+b)的结果等于( )
0 287856 287864 287870 287874 287880 287882 287886 287892 287894 287900 287906 287910 287912 287916 287922 287924 287930 287934 287936 287940 287942 287946 287948 287950 287951 287952 287954 287955 287956 287958 287960 287964 287966 287970 287972 287976 287982 287984 287990 287994 287996 288000 288006 288012 288014 288020 288024 288026 288032 288036 288042 288050 366461
| A. | -a2-b2 | B. | -a2+2ab-b2 | C. | a2-b2 | D. | a2-2ab+b2 |