【单选题】
下列函数中是奇函数的是( )
①
img class=kfformula src=zzximg/20190808/1565253233611630.png data-latex=y=5{x}^{2}/
②
img class=kfformula src=zzximg/20190808/1565253233837122.png data-latex=y=-\sqrt {x}/
③
img class=kfformula src=zzximg/20190808/1565253233536783.png data-latex=y=\frac {x} {1-{x}^{2}}/
④
img class=kfformula src=zzximg/20190808/1565253233633468.png data-latex=y=x+{x}^{2}/
【单选题】
函数img class=kfformula src=zzximg/20190808/1565253438624934.png data-latex=y=2-{x}^{2}/的单调递减区间是( )
①
img class=kfformula src=zzximg/20190808/1565253438117832.png data-latex=\left ( {0,+\infty } \right )/
②
img class=kfformula src=zzximg/20190808/1565253438467999.png data-latex=\left ( {-\infty ,0} \right )/
③
img class=kfformula src=zzximg/20190808/1565253438403956.png data-latex=\left ( {-\infty ,-1} \right )/
④
img class=kfformula src=zzximg/20190808/1565253438303182.png data-latex=\left ( {-1,+\infty } \right )/