Question

先化簡(jiǎn)，再求值：，其中x=﹣1．                  

Answer 1

【考點(diǎn)】分式的化簡(jiǎn)求值．                                                                     

【專題】計(jì)算題；壓軸題．                                                                     

【分析】這是個(gè)分式除法與減法混合運(yùn)算題，運(yùn)算順序是先乘除后加減，減法時(shí)要注意把各分母先因式分解，確定最簡(jiǎn)公分母進(jìn)行通分；做除法時(shí)要注意先把除法運(yùn)算轉(zhuǎn)化為乘法運(yùn)算，而做乘法運(yùn)算時(shí)要注意先把分子、分母能因式分解的先分解，然后約分，最后代值進(jìn)行計(jì)算．                                                       

【解答】解：原式=                         

=                                                                            

=                                                                           

=，                                                                                   

當(dāng)x=﹣1時(shí)，原式=．                                         

【點(diǎn)評(píng)】本題主要考查分式的化簡(jiǎn)求值，式子化到最簡(jiǎn)是解題的關(guān)鍵．