试说明代数式-X的平方-Y的平方+2X-4Y-17的值恒为负数
试说明代数式-X的平方-Y的平方+2X-4Y-17的值恒为负数
数学人气:168 ℃时间:2020-01-30 09:00:23
优质解答
-x²-y²+2x-4y-17=(-x²+2x-1)+(-y²-4y-4)-12=-(x²-2x+1)-(y²+4y+4) -12=-(x-1)²-(y+2)²-12=-[(x-1)²+(y-2)²]-12平方项恒非负,(x-1)²≥0 (y-2)²≥0(x-1)...
我来回答
类似推荐
猜你喜欢
- 1一列火车匀速行驶,经过一条长300M的隧道需要20S的时间,隧道的顶上有一盏灯,垂直向下发光,
- 2Will you show me your postcard?I mean__one you bought yesterday.A an B a C the D/
- 3She always looks after her little brother after school .改为同义句
- 4for,they,one,only ,$5 ,pai,r are连词成句
- 5一句话概括一个事例,写5个事例就可以了
- 61.一架飞机所带的燃料最多可以用9小时,飞机去时顺风,每小时可婔1500千米;返回时 逆风,每小时可以飞行1200千米.这架飞机最多飞出多少千米就需要往回飞?
- 7英语翻译
- 8这句英文哪里错了?when i stayed in China,i always spent my time with Lucy.
- 9吡啶和吡咯的派电子各是几个
- 10英语翻译