Question 289325: Hey guys.
Recently in a maths textbook I read something along the lines of (xy)^3 (can't figure out how to write it so that it comes up like a power, sorry). The answer, much to my disbelief, the answer was xy^3 (as I understand it should have been x^3y^3). I wrote it off as an error in the answering sheet (something that happens somewhat often) and moved on. Now, however, I've come to an example further in the book of a question written:
{(ab)^2}^-4
it then continues:
(ab^2)^-4 = a^-4 b^2*-4
= a^-4 b^-8
= 1/(a^4b^8)
This is confusing me beyond comprehension; how is {(ab)^2}^-4 equal to (ab^2)^-4? Is it equal, or have they made yet another stuff up? Normally I'd think my previous teacher taught me wrong faced with so much evidence, but I simply can't find any consistency, everything in the brackets is raised to the -4, why not the 2? Combined with the fact that this book has had three things in a row wrong before, I'm inclined to believe who ever wrote it was either tired or drunk.
My thanks;
Matt.
Found 3 solutions by scott8148, richwmiller, Alan3354:
Answer by scott8148(6628)   (Show Source):
You can put this solution on YOUR website! definitely looks hinkey to me...
the acronym for the hierarchy of operations is PEMDAS
___ Parentheses, Exponentiation, Multiplication, Division, Addition, Subtraction
the parentheses around the xy, means that they both should be cubed
can't speak for the book, but if it is consistently wrong; maybe someone just doesn't get it
___ probably not the author (hopefully)
___ could be publisher/printer; but should have been caught by proofreader...
Answer by richwmiller(17219)  (Show Source):
You can put this solution on YOUR website! Were these gaffs in the answer section in the back of the book?
Textbooks are famous for changing the problems but not changing the answers.
Answer by Alan3354(69443)  (Show Source):
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