问题
解答题
已知：关于x的方程x2-（k+2）x+2k=0；求证：无论k为任何实数值，方程总有实数根．
答案
∵△=b2-4ac
=[-（k+2）]2-4×2k
=k2-4k+4
=（k-2）2；
∴△=（k-2）2≥0，
∴无论k取任何实数时，方程总有实数根．
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已知：关于x的方程x2-（k+2）x+2k=0；求证：无论k为任何实数值，方程总有实数根．
∵△=b2-4ac
=[-（k+2）]2-4×2k
=k2-4k+4
=（k-2）2；
∴△=（k-2）2≥0，
∴无论k取任何实数时，方程总有实数根．
| 用所给的词的恰当形式填空。 | |
are two old 1. . some young boys 2. to collect stamps, but now people of all ages like collecting telephone cards. Some people even enjoy collecting kites and many other things. People like collecting things just 3. they love them, and they think that these things can bring them great 4. . |