共50条信息
下列说法正确的个数
\(①2\)的平方根是\(\sqrt{2}\) ;\(②\) \( \sqrt{5a}与 \sqrt{0.2a} \) 是同类二次根式;
\(③ \sqrt{2}-1与 \sqrt{2}+1 \)互为倒数; \(④\) \( \sqrt{3}-2 \)的绝对值是\(2- \sqrt{3} \)
如下是小明对问题作出的判断,
\((1){{a}^{0}}=1(√)\)
\((2)\sqrt{64}=\pm 8(×)\)
\((3)\)单项式\(-\dfrac{2{{x}^{2}}y}{5}\)的系数是\(-2(×)\)
\((4)\)倒数是它本身的数是\(\pm 1(√)\)
\((5)\)把\(-0.00041\)写成科学计数法是\(-4.1\times {{10}^{-4}}(√)\);
若每小题\(20\)分,则他的得分应是
定义:\(a\)是不为\(1\)的有理数,我们把\(\dfrac{1}{1-a}\)称为\(a\)的差倒数,如:\(2\)的差倒数是\(\dfrac{1}{1-2}=-1\),\(-1\)的差倒数是\(\dfrac{1}{1-(-1)}=\dfrac{1}{2}.\)已知\({{a}_{1}}=-\dfrac{1}{3}\),\(a_{2}\)是\(a_{1}\)的差倒数,\(a_{3}\)是\(a_{2}\)的差倒数,\(a_{4}\)是\(a_{3}\)的差倒数,\(……\),依此类推,则\(a_{2018}=\)________.
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