共50条信息
下列计算正确的有( )
\(①(-2)^{2}=4\)
\(②-2(a+2b)=-2a+4b\)
\(③-(-\dfrac{1}{5} )^{2}=\dfrac{1}{25} \)
\(④-(-1^{2016})=1\)
\(⑤-[-(-a)]=-a\).
观察下列算式:\(3^{1}=3\), \(3^{2}=9\), \(3^{3}=27\), \(3^{4}=81\), \(3^{5}=243\), \(3^{6}=729\), \(3^{7}=2187\),\(3^{8}=6561\),\(…\)。则\(27×9\)的个位数字是\((\) \()\)
下列说法:\(①π\)的相反数是\(-π\);\(②\)若\(\left| x \right|=\sqrt{6}\),则\(x=\sqrt{6}\);\(③\)若\(a\)为实数,则\(a\)的倒数是\(\dfrac{1}{a}\);\(④\)若\(\sqrt{{{x}^{2}}}=-x\),则\(x < 0.\)其中正确的有\((\) \()\)
进入组卷