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第,1,课时,零指数幂和负整数指数幂,1.,因为,2,5,2,5,=2,5-5,=2,0,又因为,2,5,2,5,=_,所以得,2,0,=_,同理,得,3,0,=_,5,0,=_,0,=_,【,归纳,】,a,0,=_(,a0).,语言叙述,:,一个不等于零的数的零次幂等于,_,.,1,1,1,1,1,1,1,2.,因为,2,3,2,5,=2,3-5,=2,-2,又因为,2,3,2,5,=_,所以得,2,-2,=_,同理,得,3,-2,=_,5,-1,=_,【,归纳,】,a,-p,=,_,(a0,p,是正整数,).,语言叙述,:,一个不等于零的数的,-p(p,是正整数,),次幂等于这个数,的,p,次幂的,_,.,倒数,【,预习思考,】,a,m,a,n,a,p,(a0,m,n,p,都是正整数,),的结果是什么,?,提示,:,a,m,a,n,a,p,=a,m-n-p,.,零指数幂和负整数指数幂的应用,【,例,】,计算,:(1)(-2),0,+(-1),2 013,-( ),-1,.,(2)a,6,(-a,3,),2,(-a,4,),3,.,【,解题探究,】,(1),因为,(-2),0,=,1,(-1),2013,=,-1,( ),-1,= =,-2,所以,(-2),0,+(-1),2013,-( ),-1,=,1,+,(-1),-,(-2),=,2,.,(2),因为,(-a,3,),2,=,a,6,(-a,4,),3,=,-a,12,所以,a,6,(-a,3,),2,(-a,4,),3,=a,6,a,6,(-a,12,),=a,12,(-a,12,),=,-a,0,=,-1,.,【,规律总结,】,包含零次幂和负整数指数幂的运算的三个注意,1.,顺序,:,零次幂、负整数指数幂属于乘方应先算,后算乘除,最后算加减,.,2.,法则,:,每种运算都有相应法则套用,且不可凭想当然计算,.,3.,符号,:,运算中特别注意结果的正负,.,【,跟踪训练,】,1.,下列运算中,正确的是,(,),(A)a,2,a=a,2,(B)(-a),6,a,2,=(-a),3,=-a,3,(C)a,2,a,2,=a,2-2,=0(D)(-a),3,a,2,=-a,【,解析,】,选,D.A,选项,a,2,a=a;B,选项,(-a),6,a,2,=a,6,a,2,=a,4,;C,选项,a,2,a,2,=a,2-2,=a,0,=1,所以,A,B,C,均错误,.,2.(-5),-3,等于,(,),(A)-125,(B),(C)15,(D),【,解析,】,选,B.(-5),-3,3.,计算,:(1)(-7),0,( ),-2,-3,2,(-1),2 012,.,(2)( ),5,( ),5,-(-2),-1,( ),-2,.,(3)(a,2,b,3,),-2,(a,2,b,3,),-4,.,【,解析,】,(1)(-7),0,( ),-2,-3,2,(-1),2 012,=19-91=9-9=0.,(2)( ),5,( ),5,-(-2),-1,( ),-2,=( ),5-5,-( )( ),-2,=,( ),5-5,+ 4=1+ = .,(3)(a,2,b,3,),-2,(a,2,b,3,),-4,=(a,2,b,3,),-2-(-4),=(a,2,b,3,),2,=a,4,b,6,.,1.(2012,梅州中考,)-( ),0,=,(,),(A)-2 (B)2 (C)1 (D)-1,【,解析,】,选,D.-( ),0,=-1.,2.,某种细胞的直径约为,2.410,-6,米,其中,2.410,-6,化为小数是,(,),(A)0.000 24(B)-0.000 24,(C)0.000 002 4(D)-0.000 002 4,【,解析,】,选,C.2.410,-6,=2.4 =0.000 002 4.,3.(2010,晋江中考,),计算,:3,-2,=,.,【,解析,】,3,-2,答案,:,4.,将,( ),-1,(-2013),0,(-3),2,按从小到大的顺序排列,:,.,【,解析,】,因为,( ),-1,=6,(-2 013),0,=1,(-3),2,=9,所以按从小到大的,顺序排列为,:(-2 013),0,( ),-1,(-3),2,.,答案,:,(-2 013),0,( ),-1,(-3),2,5.,计算,:(1)( ),-1,+( ),0,-( ),-1,.,(2)( ),0,+(-2),3,+( ),-1,+|-2|.,【,解析,】,(1)( ),-1,+( ),0,-( ),-1,=,(2)( ),0,+(-2),3,+( ),-1,+|-2|=1+(-8)+3+2=6+(-8)=-2.,
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