1 |
x-y |
1 |
x+y |
2x-y |
x2-y2 |
1 |
x-y |
1 |
x+y |
2x-y |
x2-y2 |
x+y+x-y |
(x+y)(x-y) |
(x+y)(x-y) |
2x-y |
2x |
2x-y |
|
|
2×2 |
2×2-1 |
1 |
3 |
A.a5•a5=2a10 | B.b4•b4=b8 | C.c4+c4=c8 | D.d3•d•d2=d5 |
A.平行四边形是中心对称图形 |
B.三角形三边的垂直平分线相交于一点,这点到三角形三个顶点的距离相等 |
C.对于简单的随机样本,可以用样本的方差去估计总体的方差 |
D.若x2=y2,则x=y |
y+3 |
x |
y |
A.-a6b3 | B.a6b | C.3a6b3 | D.-3a6b3 |
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