To learn how to factor "in pairs", tryhere.

How? Pleaseshowyour steps. Thank you!

Following the method explained in the above link, factor "in pairs":

. . . . .1 - x - x^2 + x^3

. . . . .(1 - x) - (x^2 - x^3)

. . . . .(1 - x) - x^2(1 - x)

...and so forth.