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.
Read more about this topic: FOIL Method
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 ...”)
“Within his crib is surest ward,
This little babe will be thy guard,
If thou wilt foil thy foes with joy,
Then flit not from this heavenly boy.”
—Robert Southwell (1561?–1595)