Reverse FOIL
The FOIL rule converts a product of two binomials into a sum of four (or fewer, if like terms are then combined) monomials. The reverse process is called factoring or factorization. In particular, if the proof above is read in reverse it illustrates the technique called factoring by grouping.
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Famous quotes containing the words reverse and/or foil:
“They shall beat their swords into plowshares, and their spears into pruninghooks: nation shall not lift up sword against nation, neither shall they learn war any more.”
—Bible: Hebrew Isaiah, 2:4.
The words reappear in Micah 4:3, and the reverse injunction is made in Joel 3:10 (”Beat your plowshares into swords ...”)
“Learning is, in too many cases, but a foil to common sense; a substitute for true knowledge. Books are less often made use of as “spectacles” to look at nature with, than as blinds to keep out its strong light and shifting scenery from weak eyes and indolent dispositions.... The learned are mere literary drudges.”
—William Hazlitt (1778–1830)