优优班--学霸训练营 > 知识点挑题
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            • 1.

              已知复数\(z=x+(x-a)i\),若对任意实数\(x∈(1,2)\),恒有\(|z| > \left| \left. z+i \right. \right|\),则实数\(a\)的取值范围为\((\)  \()\)

              A.\(\left( \left. -∞, \dfrac{1}{2} \right. \right]\)
              B.\(\left( \left. -∞, \dfrac{1}{2} \right. \right)\)
              C.\(\left[ \left. \dfrac{3}{2},+∞ \right. \right)\)
              D.\(\left( \left. \dfrac{3}{2},+∞ \right. \right)\)
            • 2.
              已知复数\(z=1+i\),则下列命题中正确的个数是(    )

              \(①|z|=\)\( \sqrt{2}\);\(②z=1-i\);\(③z\)的虚部为\(i\);\(④z\)在复平面内对应的点位于第一象限.

              A.\(1\)                                                             
              B.\(2\)

              C.\(3\)                                                             
              D.\(4\)
            • 3.

              已知复数\(z\)满足\(z+2i\)和\(\dfrac{z}{2-{i}}(i\)为虚数单位\()\)均为实数.

              \((1)\)求复数\(z\);

              \((2)\)若\(|z+mi|\leqslant 5\),求实数\(m\)的取值范围.

            • 4.

              设复数\(z\)满足\((1{+}i)z{=}2i\),则\({|}z{|=}({  })\)

              A.\(\dfrac{1}{2}\)
              B.\(\dfrac{\sqrt{2}}{2}\)
              C.\(\sqrt{2}\)
              D.\(2\)
            • 5.
              已知\(z_{1}\)、\(z_{2}∈C\),\(|z_{1}+z_{2}|=2 \sqrt {2}\),\(|z_{1}|= \sqrt {3}\),\(|z_{2}|= \sqrt {2}\),则\(|z_{1}-z_{2}|\)等于\((\)  \()\)
              A.\(1\)
              B.\( \dfrac {1}{2}\)
              C.\(2\)
              D.\( \sqrt {2}\)
            • 6. 复数\(Z_{1}=a+2i\),\(Z_{2}=-2+i\),如果\(|Z_{1}| < |Z_{2}|\),则实数\(a\)的取值范围是\((\)  \()\)
              A.\(-1 < a < 1\)
              B.\(a > 1\)
              C.\(a > 0\)
              D.\(a < -1\)或\(a > 1\)
            • 7.
              已知复数\(z= \dfrac {1+2i}{2-i}(i\)是虚数单位\()\),则\(|z|=\) ______ .
            • 8. 已知复数\(z=x+yi\),且\(|z-2|= \sqrt {3}\),则\( \dfrac {y}{x}\)的最大值为 ______ .
            • 9.

              已知复数\(z=1+i\),则下列命题中正确的个数是

                 \(①|z|=\sqrt{2}\);\(②\overline{z}=1-{i}\);\(③z\)的虚部为\(i\);\(④z\)在复平面内对应的点位于第一象限.

              A.\(1\)
              B.\(2\)
              C.\(3\)
              D.\(4\)
            • 10. 设复数\(z \)满足\(zi= \sqrt{3}-i (i \)为虚数单位\()\),则\(\left|z\right|= \)______
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