Question 488110
The other tutor is referring to it as FOIL (instead of foil) because FOIL is an acronym for "first, outer, inner, last," an order in which you can multiply two binomials. For example,


(-4+6i)(-3+7i) = (-4)(-3) + (-4)(7i) + (6i)(-3) + (6i)(7i)


= 12 - 28i - 18i - 42


= -30 - 46i


The textbook writers must have come up with FOIL pretty recently. I don't remember learning that acronym in my algebra class...and I'm a senior in HS so it's only been 5 or so years since I learned algebra.