(-3xy^3)^4

Would it be:
-81x^4y^12

Almost, but not quite. Just watch your negative signs.

So it would be positive?

(-)*(-)*(-)*(-)= +
right.

Thanks

Yes, that's correct! When you have a negative number raised to an even power, it becomes positive. So (-3)^4 is equal to 81.

And when you have variables with exponents inside parentheses and you raise the entire expression to a power, you multiply the exponents. In this case, (xy^3)^4 becomes x^4 * y^(3*4), which simplifies to x^4 * y^12.

Putting it all together, (-3xy^3)^4 is equal to 81x^4y^12.