【单选题】
数列的通项公式是<img class="kfformula" src="20190809/1565316958277756.png" data-latex="{a}_{n}=n\left ( {3n-1} \right )"/>,则它的第几项是70?( )
【单选题】
已知<img class="kfformula" src="20190809/1565317530438878.png" data-latex="a,b,c"/>是公比为2的等比数列,则<img class="kfformula" src="20190809/1565317530533557.png" data-latex="\frac {{b}^{2}} {ac}" width="74" height="64"/>等于( )
①
<img class="kfformula" src="20190809/1565317530127108.png" data-latex="\frac {1} {2}"/>
②
<img class="kfformula" src="20190809/1565317530414229.png" data-latex="1"/>
③
<img class="kfformula" src="20190809/1565317530771921.png" data-latex="\frac {1} {8}"/>
④
<img class="kfformula" src="20190809/1565317530451678.png" data-latex="\frac {1} {4}"/>
【单选题】
数列1,2,3,4,5,...的前10项和是( )
【单选题】
在数列<img class="kfformula" src="20190809/1565316783973080.png" data-latex="\left \{ {{a}_{n}} \right \} "/>中,前<img class="kfformula" src="20190809/1565316783992384.png" data-latex="n"/>项和公式是<img class="kfformula" src="20190809/1565316783683277.png" data-latex="{s}_{n}=4{n}^{2}-n"/>,那么<img class="kfformula" src="20190809/1565316783325652.png" data-latex="{a}_{2}"/>为( )
【单选题】
点(0,a)到原点的距离为8,则a的值为( )
【单选题】
两直线<img class="kfformula" src="20190809/1565322635666732.png" data-latex="3x+y-1=0"/>和<img class="kfformula" src="20190809/1565322635986296.png" data-latex="x+3y-1=0"/>的位置关系是( )
【单选题】
已知<img class="kfformula" src="20190809/1565322050560879.png" data-latex="A\left ( {0,-2} \right )"/>,<img class="kfformula" src="20190809/1565322050489966.png" data-latex="B\left ( {x,6} \right )"/>的中点坐标为<img class="kfformula" src="20190809/1565322050782302.png" data-latex="\left ( {-1,y} \right )"/>,则<img class="kfformula" src="20190809/1565322050701271.png" data-latex="x"/>,<img class="kfformula" src="20190809/1565322050277662.png" data-latex="y"/>的值分别为( )
①
<img class="kfformula" src="20190809/1565322050358526.png" data-latex="x=-4,y=-2"/>
②
<img class="kfformula" src="20190809/1565322050607462.png" data-latex="x=2,y=4"/>
③
<img class="kfformula" src="20190809/1565322050656212.png" data-latex="x=-4,y=25"/>
④
<img class="kfformula" src="20190809/1565322050205695.png" data-latex="x=-2,y=2"/>
【单选题】
两条平行直线<img class="kfformula" src="20190809/1565322829875215.png" data-latex="3x+4y-7=0"/>和<img class="kfformula" src="20190809/1565322829154016.png" data-latex="3x+4y+8=0"/>之间的距离是( )
①
<img class="kfformula" src="20190809/1565322829886592.png" data-latex="3"/>
②
<img class="kfformula" src="20190809/1565322829721740.png" data-latex="3\sqrt {2}"/>
③
<img class="kfformula" src="20190809/1565322829406438.png" data-latex="15"/>
④
<img class="kfformula" src="20190809/1565322829833725.png" data-latex="\frac {1} {5}" width="87" height="63"/>