Question 1:

$81x^4 - 216x^3 + 216x^2 - 96x + 16$ [4]

M3 for 4 terms correct
or for all coefficients correct except for sign errors
or for correct answer seen then further 'simplified'
or for all terms correct eg seen in table but not combined

M2 for 3 terms correct
or for correct expansion seen without correct evaluation of coefficients [if brackets missing in elements such as $(3x)^2$ there must be evidence from calculation that $9x^2$ has been used]

M1 for 1 4 6 4 1 row of Pascal's triangle seen

Guidance:
Condone eg $+(−96x)$ or $+96x$ instead of $−96x$

Any who multiply out instead of using binomial coefficients: look at their final answer and mark as per main scheme if 3 or more terms are correct, otherwise M0

Binomial coefficients such as $\binom{4}{2}$ are not sufficient – must show understanding of these symbols by at least partial evaluation