Curses! FOILed again! (Or: Random memory)

[pne]

In mathematics, when we learned to multiple expression such as (a + b) (c + d), we learned to do it with the mnemonic FOIL: first, outside, inside, last.

That is, the result is ac + ad + bc + bd: ac is the product of the first operand in each pair of parentheses (a, c), ad is the product of the "outside" ones (a, d), bc is the product of the "inside" ones, and bd is the product of the last operand (b, d).

Basically, a systematic way to ensure that you don't miss any combinations by doing them in a specific order each time.

Comments

[ladyortyger.livejournal.com]

We learned that too. ;) aww.. nostalgia. I haven't taken an algebra based class in .. long time now.

[eridanusus.livejournal.com]

Dat couldn't remember the formula we got taught because he never went to maths. We had BEDMAS - brackets, e-things (squared, cubed, etc), division/multiplication, addition/subtraction.

Chris

mathematical mnemonics

[pne.livejournal.com]

Ah, a mnemonic for remembering the order of evaluation.

Which reminds me of another mnemonic we learned in maths: "SOH CAH TOA", for the three main trigonometric relations: sine = opposite/hypotenuse; cosine = adjacent/hypotenuse; tangent = opposite/adjacent.