close
標題:
help me 唔識計
發問:
24 1) 625(5^3x -125^x+1) = - 4 ------ 25 2) 5(4^x+1) -4(2^2x-1)=288
最佳解答:
1)625(53x –125x+1) = - 124 / 25 53x – 53x+3 = - 124 / 15625 53x ( 1 - 53 ) = - 124 / 15625 53x = 1 / 15625 53x = 1 / 56 53x = 5-6 3x = -6 x = -2 2) 5(4x+1) -4(22x-1)=288 5(22x+2 ) – 4 ( 22x-1 ) = 288 5 ( 22x )( 22 ) – 4 ( 22x )( 2-1 ) = 288 22x [ ( 5 )( 4 ) – 4 ( 2-1 ) ] = 288 22x ( 18 ) = 288 22x = 16 22x = 24 2x = 4 x = 2 2007-09-24 00:02:41 補充： 其實只要運用指數法則中: a^( m + n ) = a^m x a^n, 抽出common factor, 便可求出答案。
其他解答:
help me 唔識計
發問:
24 1) 625(5^3x -125^x+1) = - 4 ------ 25 2) 5(4^x+1) -4(2^2x-1)=288
最佳解答:
1)625(53x –125x+1) = - 124 / 25 53x – 53x+3 = - 124 / 15625 53x ( 1 - 53 ) = - 124 / 15625 53x = 1 / 15625 53x = 1 / 56 53x = 5-6 3x = -6 x = -2 2) 5(4x+1) -4(22x-1)=288 5(22x+2 ) – 4 ( 22x-1 ) = 288 5 ( 22x )( 22 ) – 4 ( 22x )( 2-1 ) = 288 22x [ ( 5 )( 4 ) – 4 ( 2-1 ) ] = 288 22x ( 18 ) = 288 22x = 16 22x = 24 2x = 4 x = 2 2007-09-24 00:02:41 補充： 其實只要運用指數法則中: a^( m + n ) = a^m x a^n, 抽出common factor, 便可求出答案。
其他解答:
此文章來自奇摩知識+如有不便請留言告知
1) x = -2 2) x = 2
文章標籤
全站熱搜
留言列表
