You must have 4 terms for factoring by grouping to be easier to use.
For example...
x^2 + 10x + 2x + 20
(x^2 + 10x) + (2x + 20)
x(x+10) + 2(x+10)
(x+2)(x+10)
The first line, the expression x^2+10x+2x+20, has four terms.
Note: Just because you have four terms doesn't automatically guarantee you can factor
