1) True or False (If false, tell why) : The graph of a nonzero function cannot be symmetric with respect to the x-axis.
2) It is possible for the solution set of a quadratic equation with real coefficients to consist of a one real number and one nonreal complex number? Please explain.
3) Explain the error in the following work.
1/9 < 1/3
(1/3)^2 < 1/3
log (1/3)^2 < log 1/3
2log 1/3 < 1 log 1/3
2 < 1
Thank you very much!
3 maths questions (15points)
2010-09-20 12:41 am
回答 (1)
2010-09-20 1:27 am
✔ 最佳答案
1)False.
For instance, the graph y^2=x is symmetric with respect to x-axis.
2)
If a complex number a+bi is the root of the quadratic equation, then its conjugate must also be the root of the equation.
Hence, if one of the roots is a complex number, then the other one must also be a complex number, so the ans. is not possible.
3)
It's because log 1/3<0
When both sides are divided by log 1/3, then the inequality sign should be changed.
2log 1/3 < 1 log 1/3 => 2>1
收錄日期: 2021-04-22 00:51:11
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100919000051KK01235