整式的乘法同底数幂的乘法ppt课件.ppt
同底数幂的乘法,永九中 饶俊容,光的速度约为3105千米/秒,太阳光照射到地球大约需要5102秒.地球距离太阳大约有多远?,光的速度约为3105千米/秒,太阳光照射到地球大约需要5102秒.地球距离太阳大约有多远?,(3105) (5102) =,(35) (102105),102105等于多少呢?,猜想: am an= ? (当m、n都是正整数),(1)102103(2)a5a8(3)10m10n,指数,幂,底数,=(1010)(101010),=1010101010,=105,(1),=102+3,=(101010)(101010),5个10,8个10,=101010,13个10,(2)105 108,=105+8,(3)10m 10n,=(101010)(101010),m个10,n个10,=101010,m+n个10,am an,=am+n,am an = am+n (当m、n都是正整数),同底数幂相乘,,底数,指数。,不变,相加,同底数幂的乘法性质:,如 4345=,43+5,=48,幂的底数必须相同,相乘时指数才能相加.,同底数幂,口答,=105+6= 1011,=a7+3= a10,= x5+5=x10,=b5+1= b6,(2) a7 a3,(3) x5 x5,(4) b5 b,(1) 105106,(5)10102104,(6) x5 x x3,=101+2+4=107,=x5+1+3=x9,(7) a7 a3,=a7+3= a10,(8) x5 a5,= x5+5=x10,判断(正确的打“”,错误的打“”),x3x5=x15 ( ) (2) xx3=x3 ( )(3) x3+x5=x8 ( ) (4)x2x2=2x4 ( )(5)(-x)2 (-x)3 = (-x)5= -x5 ( ) (6)a3a2 - a2a3 = 0 ( ) (7)a3b5=(ab)8 ( ) (8) y7+y7=y14 ( ),计算: (-3)7(-3)6 ; (2) 10310;(3) -x3x5; (4) b2mb2m-1.,解:(1) (-3)7(-3)6=(-3)7+6=(-3)13,(2) 10310=103+1=104,(3)-x3 x5 = -x3+5 = -x8,(4) b2m b2m-1 = b2m+2m-1= b4m-1,填空1:(1)x5 ( )=x 8 (2)a ( )=a6(3)x x3( )= x7 (4)xm ( )3m(5)x5x( )=x3x7=x( ) x6=xx( )(6)an+1a( )=a2n+1=aa( )(7)a2na( )=an+2a( ) =a2n+2=a( ) an+1,x3,a5,x3,2m,5 4 9,n 2n,2 n n+1,填空2:(1) 8 = 2x,则 x = ;(2) 8 4 = 2x,则 x = ;(3) 3279 = 3x,则 x = .,3,5,6,23,23,3,25,36,22,=,33,32,=,小 结,同底数幂的乘法性质:,底数 ,指数 .,不变,相加,幂的意义:,= aa a,n个a,