x |
3 |
y |
4 |
z |
5 |
xy+yz+zx |
x2+y2+z2 |
x |
3 |
y |
4 |
z |
5 |
xy+yz+zx |
x2+y2+z2 |
3k?4k+4k?5k+5k?3k |
(3k)2+(4k)2+(5k)2 |
47k2 |
50k2 |
47 |
50 |
14xy(x+y)3 |
4x2(x+y)2 |
2x |
x+y |
A.扩大两倍 | B.不变 | C.缩小两倍 | D.不能确定 |
x+y |
2x |
A.扩大3倍 | B.不变 | C.缩小3倍 | D.缩小6倍 |
ab |
a+b |
A.是原来的2倍 | B.原来的4倍 | ||
C.是原来的
| D.不变 |
b2+c2 |
a2 |
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