If you multiply four negative numbers, what is the sign of the product?
You can test this with numbers, the easiest with -1:
(-1)(-1)(-1)(-1) = (1)(-1)(-1) = (-1)(-1) = 1
General:
(-a)(-b)(-c)(-d) = abcd
The sign of the product of four negative numbers is positive.
If you multiply five negative numbers, what is the sign of the product?
Testing with -1:
(-1)(-1)(-1)(-1)(-1) = (1)(-1)(-1)(-1) = (-1)(-1)(-1) = (1)(-1) -1
General:
(-a)(-b)(-c)(-d)(-e) = -abcde
The sign of the product of five negative numbers is negative.
General rule: The product of an even number of negative numbers is positive. The product of an odd number of negative numbers is negative.
