文档介绍：::B≠0分式无意义的条件:B=:A=0且B≠0A>0,B>0或A<0,B<0A>0,B<0或A<0,B>0分式<0的条件:>0的条件:ABAB形如,其中A,B都是整式,(1)(2)(3)(4)(5)是分式的有个。32x32xx2x2x∏1-,分式有意义.(1)(2)(3)(4)X-1X+2X2-14xX-11X2-2x+()ABCDX+1x2X+1X2+1X-1X2+11X-1练****3Bx≠-2x≠±1x≠±,+y2x-,下列分式的值为0?(1)(2)(3)(4)X-4X+1X-2X-1X-3X-3X2-1X2+2x+12x=yX=4X=1X=-3X=,分式(1)有意义(2)值为02x(x-2)5x(x+2),则x的取值范围是1-x-2X≠0且x≠-2X=2X>,+1X+,-7X2+,+1X2-2x+3<-2≥7>-:分式的分子与分母同乘以(或除以)分式的值用式子表示:(其中M为的整式)ABAXM()ABA÷M()==:AB=B()=A()=-A()-A-B=A()=B()=-A()一个不为0的整式不变BXMB÷M不为0-A-B-BB-.(2)(3)(4)a+bab=a2b()ab+b2ab2+b=a+b()a-ba+b=a2–b2()a+bab=2a2+2ab()a2+abab+1a2+b2-()ABCDab=a2b2a-ba=a2-ba22-xX-1=X-21-x42a+b=2a+:-a-bc-d=a+b()-x+yx+y=x-y()Cd-c-x-( )A B C D2m-34-m4-m3-2m2m-34-m3-2m4-m3-2mm-( )-x+y-x-y-x+y-x-y-x+y-x-y-x+y-x-y=X-yX+y=-x-yX+y=X+yX-y=X-yX+yABCDAA