7. a. Use the binomial theorem to expand
$$( 8 - 3 x ) ^ { \frac { 2 } { 3 } }$$
in ascending powers of \(x\), up to and including the term \(x ^ { 3 }\), as a fully simplifying each term.
Edward, a student decides to use the expansion with \(x = \frac { 1 } { 3 }\) to find an approximation for \(( 7 ) ^ { \frac { 2 } { 3 } }\). Using the answer to part (a) and without doing any calculations, b. explain clearly whether Edward's approximation will be an overestimate, or, an underestimate.