Easy -1.3 This is a straightforward application of the binomial theorem with a small positive integer power (n=4) and simple coefficients. It requires only direct substitution into the binomial formula and basic arithmetic to simplify coefficients—no problem-solving or conceptual insight needed, making it easier than average.
B3 for 4 terms correct, or B2 for 3 terms correct or for all correct but unsimplified (may be at an earlier stage, but factorial or \(^nC_r\) notation must be expanded/worked out); or B1 for 1, 4, 6, 4, 1 soi or for \(1 + \ldots + \frac{1}{16}x^4\) [must have at least one other term]
## Question 9:
$1 + 2x + \frac{3}{2}x^2 + \frac{1}{2}x^3 + \frac{1}{16}x^4$ oe (must be simplified) isw | **B4** | **B3** for 4 terms correct, or **B2** for 3 terms correct or for all correct but unsimplified (may be at an earlier stage, but factorial or $^nC_r$ notation must be expanded/worked out); or **B1** for 1, 4, 6, 4, 1 soi or for $1 + \ldots + \frac{1}{16}x^4$ [must have at least one other term]
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