Confuse in math! when do u use negative sign

(-m^3n^2)^2 (-10m^4n^5)
= -10m^10n^9
our teacher said that's the right answer.
my question is...
how come we still remain the negative sign? shouldn't it be positive 10m^10n^9? i thought that negative times negative is equal to positive...
like this: (-1)(-10)=10...right? but how come in that equation it's like that?

:)

You actually have 3 negative signs:

(-m^3n^2)^2 expands to

(-m^3n^2) * (-m^3n^2)
= m^6n^4

Then you multiply this by the final bit
(m^6n^4) * (-10m^4n^5)
= -10m^10n^9

Hi,

You have to eliminate negative exponents in an answer, but negative coefficients are perfectly fine in your answers.

I hope that helps!! :-)