Directions: Use the integers -9 to 9, at most one time each, to fill in the boxes twice: once to make a positive real number product and once to make a negative real number product.
How can we accomplish that?
An example of a negative product is (-6 + 4i)(3 + 2i). This has a product of -18 + -12i + 12i + 8i^2 which is equivalent to -18 + 8i^2 or -26.
An example of a positive product is (6 + 4i)(3 + -2i). This has a product of 18 + -12i + 12i + -8i^2 which is equivalent to 18 + -8i^2 or 26.
Source: Robert Kaplinsky