-208
Explanation:
If the complete expression is a³ – 6³
then a³ – 6³ with a being equal to 2 is
(2)³ – (6)³ =
(2 × 2 × 2) – (6 × 6 × 6)
=
(4 × 2) – (36 × 6)
=
(8) – (216)
=
-208
This is done with substitution, just do the arithmetic with 2 in the place of a.
