2x |
x+y |
A.扩大3倍 | B.缩小3倍 | C.缩小6倍 | D.不变 |
2x |
x+y |
6x |
3x+3y |
2x |
x+y |
xy |
2x+3y |
A.不变 | B.扩大5倍 | C.缩小5倍 | D.扩大10倍 |
2a |
a+b |
A.是原来的20倍 | B.是原来的10倍 | ||
C.是原来的
| D.不变 |
x |
x+y |
A.扩大10倍 | B.缩小10倍 | C.扩大2倍 | D.不变 |
b |
a |
ab |
a() |
| ||
a+b |
() |
2a+2b |
3a+3b |
9c |
a+b |
() |
x |
3 |
y |
4 |
z |
5 |
xy+yz+zx |
x2+y2+z2 |
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