That's really the only "shortcut" you need to know. The only other one I can think of is the extension of the example you quoted using three roots i.e.
a2 + b2 + c2 = (a + b + c)2 - 2(ab + bc + ac)
That's really the only "shortcut" you need to know. The only other one I can think of is the extension of the example you quoted using three roots i.e.
a2 + b2 + c2 = (a + b + c)2 - 2(ab + bc + ac)