1. Why is the answer a negative number?

(-5a^3b^5)^2 / a^4b^3

(-5a^3b^5)(-5a^3b^5) / a^4b^3

25a^6b^10 / a^4 b^3

= 25a^2b^7

The book says the answer= -25a^2b^7

2. Re: Why is the answer a negative number?

Originally Posted by einstein
(-5a^3b^5)^2 / a^4b^3

(-5a^3b^5)(-5a^3b^5) / a^4b^3

25a^6b^10 / a^4 b^3

= 25a^2b^7

The book says the answer= -25a^2b^7
Following PEMDAS - both you and book are incorrect (according to the problem as posted).

3. Re: Why is the answer a negative number?

Originally Posted by einstein
(-5a^3b^5)^2 / a^4b^3
Book is correct IF this is the expression: -(5a^3b^5)^2 / (a^4b^3)
In other words: the - sign outside the brackets, PLUS denominator MUST be bracketed

4. Re: Why is the answer a negative number?

Originally Posted by Subhotosh Khan
Originally Posted by einstein
(-5a^3b^5)^2 / a^4b^3

(-5a^3b^5)(-5a^3b^5) / a^4b^3

25a^6b^10 / a^4 b^3

= 25a^2b^7

The book says the answer= -25a^2b^7
Following PEMDAS - both you and book are incorrect (according to the problem as posted).

5. Re: Why is the answer a negative number?

Originally Posted by einstein

If you did - read it again slowly and carefully ......

6. Re: Why is the answer a negative number?

Originally Posted by Subhotosh Khan
Originally Posted by einstein

If you did - read it again slowly and carefully ......

he said the book is correct if there is a negative sign before the bracket and brackets around the last two terms... but there is not. i copied the the question from the book to the forum correctly and always do

so denis is saying IF the book did it this way then the books answer is right. But the book did not do it the way he wrote, so that means the books answer is wrong. i got that!

but you said BOTH the book's anwer was wrong (which, like i said, i get it) but you also said my answer was wrong. So i said please elaborate because i don't see how my answer is wrong. I believe i followed pemdas correctly. If you would kindly point out why MY answer was wrong i'd much appreciate it.

7. Re: Why is the answer a negative number?

25a^6b^10 / a^4 b^3
= 25a^2b^7

That is incorrect (sorry, man!)
As is (no brackets) 25a^6b^10 / a^4 b^3 means (25a^6b^10 / a^4) times b^3

8. Re: Why is the answer a negative number?

Originally Posted by Denis
25a^6b^10 / a^4 b^3
= 25a^2b^7

That is incorrect (sorry, man!)
As is (no brackets) 25a^6b^10 / a^4 b^3 means (25a^6b^10 / a^4) times b^3
thanks.

so the answer to 25a^6b^10 / a^4 b^3 = 25a^2b^13

9. Re: Why is the answer a negative number?

YESssssssssss

10. Originally Posted by einstein

i copied the the question from the book to the forum correctly and always do
If your book displays the given expression as shown below, then you did not correctly copy the exercise.

$\frac{(-5 a^3 b^5)^2}{a^4 b^3}$

If your book displays the given expression the following way, instead, then you could clarify your typing with square brackets as shown in blue.

$\frac{(-5 a^3 b^5)^2}{a^4} \; b^3$

[(-5a^3b^5)^2/a^4] b^3

Either way, the factor of -1 is squared, so there is no negation sign in the answer.

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