【正文】
(2 m ) 3 = a 3 , 2 10 n = (2 5 n ) 2 = (32 n ) 2= b 2 ,所以 2 3 m + 10 n = 2 3 m 2 n + (2 n ) 2 ( - x ) 7 + 5 ( x 4 ) 4 - ( x 8 ) 2 ; 解:原式=- 7 x 16 + 5 x 16 - x 16 =- 3 x 16 ; ( 3 ) [ ( x + y ) 3 ] 6 + [ ( x + y ) 9 ] 2 ; ( 用 x + y 的冪表示 ) 解:原式= ( x + y ) 18 + ( x + y ) 18 = 2( x + y ) 18 ; ( 4 ) 2 ( a 5 ) 2 x4= x7 D . 2 x3- x3= 1 10. 下列四個(gè)算式中正確的有 ( ) ① ( a4)4= a4 + 4= a8; ② [ ( b2)2]2= b2 2 2= b8; ③ [ ( - x )3]2= ( - x )6= x6; ④ ( - y2)3= y6. A . 0 個(gè) B . 1 個(gè) C . 2 個(gè) D . 3 個(gè) C C 1 1. 計(jì)算 ( - x5)7+ ( - x7)5的結(jié)果是 ( ) A .- x13 B . - 2 x35 C .- 2 x70 D . 0 12. 已知 a =- 34, b = ( - 3 )4, c = ( 23)4, d = ( 22)6,則下列 a , b , c , d 四者關(guān)系的判斷,正確的是 ( ) A . a = b , c = d B . a = b , c ≠