Prove, from first principles, that the derivative of \(3 x ^ { 2 }\) is \(6 x\).
(a) Find the first 3 terms, in ascending powers of \(x\), of the binomial expansion of \(\left( 2 - \frac { x } { 2 } \right) ^ { 7 }\), giving each term in its simplest form.
(b) Explain how you would use your expansion to give an estimate for the value of \(1.995 ^ { 7 }\)