A friend is taking a college algebra class and they are teaching him that
$$-3^2 = -9$$
Their explanation is:
$$-3^2 = -(3^2) = -9.$$
It has been a long time for me but I thought that in the absence of any parenthesis that:
$$-3^2 = (-3) \times (-3) = 9.$$
They are even contradicting themselves because they teach the odd/even shortcut for exponents in another part of the book. i.e.:
if the exponent is even, the result it positive, and if the exponent is odd the result is negative.
This is an actual picture of the book where they contradict themselves on the $-3^2 = -9$:
edit OK, since this has generated way more attention then I ever imagined I've updated here to respond to some of the comments.
1) I understand why the book is not contradicting itself in the picture specifically, or even in the "odd/even" exponent context, due to the fact that variable substitution always implies parens. The book and the teacher, from what my friend has said, do not do a good job of explaining that distinction though.
2) Yes, I understand why the answer is that $-3^2$ is NOT ambiguous is due to order of operations.
3) I made a comment about Khan Academy teaching it incorrectly, I realized I was wrong once I re-watched the video.