/sci/ - Science & Math

I need recs of books about teaching high school and middle school maths.
Essentially, my little sister has been having issues with the usual high school stuff and shaky foundations.
Thanks in advance.
>>11104192
>desperate
Probably.
I really just don't know where it is they got my email.
>>11105518
I think so. Check with wolfram.
>>11105783
i is neither surjective nor injective. 1 x 2 = 2 x 1. 17 isn't in the image.
ii is injective, but not surjective. {1, 3} isn't in the image.
iii isn't injective or surjective. [math]f_3(2, 1)=f(1, 3)[/math] . 1 isn't in the image.
iv isn't surjective. 1 isn't in the image. I'm pretty sure it's also not injective, but no immediate counterexample comes to mind.

I)trivial and left to the reader as an exercise.
II) [math]{0} \rightarrow [0, 1] \rightarrow {0}[/math], where the first map is the identity, and the second map is constant zero.
>>11106514
>randomly between t_1 and t_2 sec
Be specific.
>>11107651
Yes.
See: http://www.sciencedirect.com/science/article/pii/0012365X95000725/pdf?md5=8ec3598f1533fd0e2fed6477a8426d0a&pid=1-s2.0-0012365X95000725-main.pdf , theorem 18.
And thus concludes my short foray into graph theory. Hopefully never to happen again.