9o既x次方加9o既x次方減一次方再減10=0
求x等於幾多~
中三數學題一題
2007-01-14 9:50 pm
回答 (6)
2007-01-14 10:05 pm
✔ 最佳答案
9x + 9x-1 - 10 = 09x + 9x-1 = 10
9x + 9x ÷ 91 = 10
9x (1 + 1 ÷ 9) = 10
9x = 10 ÷ (1 + 1 ÷ 9)
9x = 10 ÷ (9 ÷ 9 + 1 ÷ 9)
9x = 10 ÷ [(9 + 1) ÷ 9]
9x = 10 ÷ (10 ÷ 9)
9x = 10 x (9 ÷ 10)
9x = 9
9x = 91
x = 1
2007-01-14 10:01 pm
9^x + 9 ^x -9+10=0
2(9^x)=19
xlog9=log9.5
x=1.024607053
P.S : 9^x係9 ge x次方
2(9^x)=19
xlog9=log9.5
x=1.024607053
P.S : 9^x係9 ge x次方
2007-01-14 10:00 pm
其實呢 d 問題, 你係要明白佢係做咩, 而唔係求 solution ... 當 9的x次方 係一個未知數
ｘ ｘ－１
９ ＋ ９ ＝ １０
ｘ ｘ
９ ＋ （ ９ ）／９ ＝ １０
ｘ
９ （ １ ＋ １／９ ）＝ １０
ｘ
９ ＝ ９
take LOG on both sides, Ｘ ＝ １
如果你不明白，可以 e-mail 我
ｘ ｘ－１
９ ＋ ９ ＝ １０
ｘ ｘ
９ ＋ （ ９ ）／９ ＝ １０
ｘ
９ （ １ ＋ １／９ ）＝ １０
ｘ
９ ＝ ９
take LOG on both sides, Ｘ ＝ １
如果你不明白，可以 e-mail 我
2007-01-14 9:58 pm
9^x+9^x-1-10=0
9^x+9^x乘1 over 9-10=0
9^x(1+1over 9)=10
9^x=10除10 over 9
3^3x= 3^3
3X=3
x=1
9^x+9^x乘1 over 9-10=0
9^x(1+1over 9)=10
9^x=10除10 over 9
3^3x= 3^3
3X=3
x=1
2007-01-14 9:56 pm
9^x + 9^(x-1) -10=0
9^x-1 乘(9 +1) = 10
9^x-1 乘10 = 10
9^x-1 = 1
9^x-1 = 9^0 (9既0次方=1)
所以x-1=0
.......x=1
2007-01-14 13:58:50 補充：
加番d解釋:9^x 9^(x-1) -10=09^x-1 乘(9 1) = 10 (抽個 9^x-1出黎做common factor)9^x-1 乘10 = 10 9^x-1 = 1 (兩面除左10之後既結果)9^x-1 = 9^0 (9既0次方=1)所以x-1=0 .......x=1
2007-01-14 14:41:52 補充：
lee題數中三嫁咋wo.....講log....好似唔關事.....
9^x-1 乘(9 +1) = 10
9^x-1 乘10 = 10
9^x-1 = 1
9^x-1 = 9^0 (9既0次方=1)
所以x-1=0
.......x=1
2007-01-14 13:58:50 補充：
加番d解釋:9^x 9^(x-1) -10=09^x-1 乘(9 1) = 10 (抽個 9^x-1出黎做common factor)9^x-1 乘10 = 10 9^x-1 = 1 (兩面除左10之後既結果)9^x-1 = 9^0 (9既0次方=1)所以x-1=0 .......x=1
2007-01-14 14:41:52 補充：
lee題數中三嫁咋wo.....講log....好似唔關事.....
2007-01-14 9:56 pm
x=2次方
收錄日期: 2021-04-12 17:53:25
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070114000051KK02090