)?°??????????????????????°????±
????×ì?????é??
?????·???????÷???ó??????±????????????????????°??°???
???¨?????ì????????
(?
)?°°????è?????????????ù????????????????×??????????????????±
???ò?±??????????
?????á??????????
???à?????????????????°°?????°??????????????¤±???×????????????????±
???°????°????????????ì??
???????????????????????ó??????????????????±?????
???¤?è??°??è????????
???????????????????????ù×???????????
???à???????????ó??
???????????????????ú×?×?????????????
???????°±?????????????±????????????????¨?????????????????¨?????ò????°???
·??????????????????????ú×?×????????????????????í???????????????×°?????
????????????????
???ó??×???????????°???
????????×????????à???ü???×??????×?????×?????×????ú?°??
???à????????????????????????????
?°?????????????????????????·??????°???????????°????±
?°?????????????????·?????ó?¤???????????±
?°?ê???????????????????????ù???ê?á????°????±
?????±???·???ú?????????????°???????·??????????????????°??????????????±
?°?????????????????????ú??±????ú????????×????????±
??×??????ì???????????????é???ú??°?±?????·??????ó??×????????????à????è???
(
)-??????-x2
???é??×?????????×ù?á??????????????
????×ì???±?é????????????×?????????±?°???
???????????é?ó??×?????????
·ò??????????????????????????????
????????????????????
??????????°???×???????????×?°???
?°????????????????????????°????????????é????????????????
???¨??×????????????é??×??????±?±???????ú??
×?????????????????????°???×???±???°???
???????ù?÷????????×??????????????à?????????ü?????ü°???
?????????÷?????????é??×???×???°??è???????????????à????????
???????à???????ó????
?°°????????è????????????????????°????????????????±
??è??ü?????????°?????????????????????????????????????±
?°???????ê?????¨????????×??????????????????????????????ì??