find all real solution of the equation log(7-x)=(log(7-x))的2次方. explain carefully why each step of your algebraic solving procedure is justified.
please steps by steps!
我有一個數學問題~急死了><!
2012-05-01 11:04 pm
回答 (3)
2012-05-01 11:20 pm
✔ 最佳答案
log(7-x)=[log(7-x)]^2 所以7-x>0 x<7log(7-x)=[log(7-x)]^2
[log(7-x)]^2-log(7-x)=0
[log(7-x)][log(7-x)-1]=0
所以log(7-x)=0或[log(7-x)]-1=0
7-x=1或7-x=10 已知log1=0 log10=1
x=6或-3......ans
2012-05-01 20:16:40 補充：
0^2=0 為何捨棄不要?
2012-05-02 3:55 am
log(7-x)=[log(7-x)]^2 >>> 7-x>0 x<7
log(7-x)=[log(7-x)]^2
[log(7-x)]^2-log(7-x)=0
[log(7-x)][log(7-x)-1]=0
log(7-x)=0 or [log(7-x)]-1=0
7-x=1 or 7-x=10
且log10=1 log1=0
故x=6或-3
但6不合(帶回原式)
0不等於0的平方
ANS~~:-3
log(7-x)=[log(7-x)]^2
[log(7-x)]^2-log(7-x)=0
[log(7-x)][log(7-x)-1]=0
log(7-x)=0 or [log(7-x)]-1=0
7-x=1 or 7-x=10
且log10=1 log1=0
故x=6或-3
但6不合(帶回原式)
0不等於0的平方
ANS~~:-3
2012-05-01 11:13 pm
What's the base? Is it e or 10?
收錄日期: 2021-04-13 18:39:49
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