Question

Check please??
1. Can it ever be true that |a| = -a for real number a? Explain.
my answer: yes, if a < 0.
2. is it possible for a real number to be both rational and irrational? Explain.
my answer: no, b/c rational #s can be written as a fraction and irrational #s cannot.
Thank you!

Answer 1

I think |0|= -0, so how about a≤0 ?

Answer 2

2. is correct.

Answer 3

okay, thanks! but my book said for #1 yes, |a| = -a if a < 0.

Answer 4

For 1. I agree with @phi, not with your book.

Answer 5

okay, thank you both! :)

Answer 6

Interesting. Wolfram says otherwise
http://www.wolframalpha.com/input/?i=for+real+x%2C++solve+%7Cx%7C+%3D+-x

Answer 7

wlcm