<em><span style、"font-family: 'times new roman', times, serif;">x</span></em>=0
<em><span style、"font-family: 'times new roman', times, serif;">x</span></em>=1
<em><span style、"font-family: 'times new roman', times, serif;">x</span></em>=-1
<em><span style、"font-family: 'times new roman', times, serif;">x=e</span></em>