先化简,再求值:1/a-√1/a²+a²-2,其中a=1/5 (√表示根号)请尽快!提示:当a为实数时,√a²=|a|=a (a>0),0 (a=0),-a (a<0).
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![先化简,再求值:1/a-√1/a²+a²-2,其中a=1/5 (√表示根号)请尽快!提示:当a为实数时,√a²=|a|=a (a>0),0 (a=0),-a (a<0).](/uploads/image/z/2742698-2-8.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC%EF%BC%9A1%2Fa-%E2%88%9A1%2Fa%26%23178%3B%2Ba%26%23178%3B-2%2C%E5%85%B6%E4%B8%ADa%3D1%2F5+%EF%BC%88%E2%88%9A%E8%A1%A8%E7%A4%BA%E6%A0%B9%E5%8F%B7%EF%BC%89%E8%AF%B7%E5%B0%BD%E5%BF%AB%21%E6%8F%90%E7%A4%BA%EF%BC%9A%E5%BD%93a%E4%B8%BA%E5%AE%9E%E6%95%B0%E6%97%B6%EF%BC%8C%E2%88%9Aa%26%23178%3B%3D%7Ca%7C%3Da+%EF%BC%88a%EF%BC%9E0%EF%BC%89%2C0+%28a%3D0%29%2C-a+%28a%EF%BC%9C0%29.)
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先化简,再求值:1/a-√1/a²+a²-2,其中a=1/5 (√表示根号)请尽快!提示:当a为实数时,√a²=|a|=a (a>0),0 (a=0),-a (a<0).
先化简,再求值:1/a-√1/a²+a²-2,其中a=1/5 (√表示根号)请尽快!
提示:当a为实数时,√a²=|a|=a (a>0),
0 (a=0),
-a (a<0).
先化简,再求值:1/a-√1/a²+a²-2,其中a=1/5 (√表示根号)请尽快!提示:当a为实数时,√a²=|a|=a (a>0),0 (a=0),-a (a<0).
1/a-√1/a²+a²-2,
=1/a-√(a-1/a)²
因a=1/5 1/a=5,
所以原式=1/a-(1/a-a)
=1/a-1/a+a
=a
=1/5
1/a-√1/a²+a²-2
=1/a-1/a+a²-2
=a²-2
=1/25-2
=-49/25
当a>0时,√1/a²=1/a,
∴当a=1/5时,原式=1/a-1/a+a²-2=a²-2=1/25-2=-49/25。
如果是1/a-√(1/a²+a²-2),
则原式=1/a-√(a-1/a)²,
因a=1/5 ,1/a=5,
所以原式=1/a-(1/a-a)
=1/a-1/a+a
=a
=1/5。
对不起,我还没有学呢