OCR PURE — Question 1 2 marks

Exam BoardOCR
ModulePURE
Marks2
PaperDownload PDF ↗
TopicBinomial Theorem (positive integer n)
TypeStandard binomial expansion coefficient
DifficultyModerate -0.8 This is a straightforward application of the binomial theorem requiring identification of the correct term (r=3) and calculation using the formula. It's simpler than average as it involves only one specific term with small numbers and no algebraic manipulation beyond the basic formula.
Spec1.04a Binomial expansion: (a+b)^n for positive integer n
1 Find the term in \(x ^ { 3 }\) in the binomial expansion of \(( 3 - 2 x ) ^ { 5 }\).
Question 1:
AnswerMarks Guidance
AnswerMarks Guidance
\(^5C_2 \times 3^2 \times (-2x)^3\)B1 \(^5C_2\) or \(^5C_3\) soi, or \(3^2 \times (-2x)^3\), or \(\pm720\) soi
\(= -720x^3\) ISWB1 cao
[2] 
## Question 1:

| Answer | Marks | Guidance |
|--------|-------|----------|
| $^5C_2 \times 3^2 \times (-2x)^3$ | B1 | $^5C_2$ or $^5C_3$ soi, or $3^2 \times (-2x)^3$, or $\pm720$ soi |
| $= -720x^3$ ISW | B1 | cao |
| **[2]** | | |

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1 Find the term in $x ^ { 3 }$ in the binomial expansion of $( 3 - 2 x ) ^ { 5 }$.

\hfill \mbox{\textit{OCR PURE  Q1 [2]}}
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