Easy -1.2 This is a straightforward application of the binomial theorem with a small positive integer power (n=4). It requires only direct substitution into the formula and simplification of coefficients—no problem-solving or insight needed, just mechanical execution of a standard technique taught early in C1.
M3 for 4 terms correct or all coefficients correct except sign errors
for binomial coefficients, \(^4C_2\) or factorial notation not sufficient; accept \(\frac{4\times3\times2\times1}{2\times1\times2\times1}\) oe etc [4]
M2 for 3 terms correct or correct expansion without correct evaluation of coefficients
M1 for \(1\ 4\ 6\ 4\ 1\) soi in Pascal's triangle or in expansion where powers of 5 ignored
# Question 6:
$1-20x+150x^2-500x^3+625x^4$ as final answer | M3 for 4 terms correct or all coefficients correct except sign errors | for binomial coefficients, $^4C_2$ or factorial notation not sufficient; accept $\frac{4\times3\times2\times1}{2\times1\times2\times1}$ oe etc [4]
| M2 for 3 terms correct or correct expansion without correct evaluation of coefficients |
| M1 for $1\ 4\ 6\ 4\ 1$ soi in Pascal's triangle or in expansion where powers of 5 ignored |
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