CAIE P1 2003 November — Question 4 6 marks

Exam BoardCAIE
ModuleP1 (Pure Mathematics 1)
Year2003
SessionNovember
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicStandard Integrals and Reverse Chain Rule
TypeFind curve equation from derivative (extended problem with normals, stationary points, or further geometry)
DifficultyEasy -1.2 This is a straightforward integration question requiring only basic polynomial integration and using an initial condition to find the constant. Part (ii) involves solving a simple quadratic inequality. Both parts are routine textbook exercises with no problem-solving insight required, making this easier than average.
Spec1.02g Inequalities: linear and quadratic in single variable1.08a Fundamental theorem of calculus: integration as reverse of differentiation

4 A curve is such that \(\frac { \mathrm { d } y } { \mathrm {~d} x } = 3 x ^ { 2 } - 4 x + 1\). The curve passes through the point \(( 1,5 )\).
  1. Find the equation of the curve.
  2. Find the set of values of \(x\) for which the gradient of the curve is positive.

(i) \(y = x^3 - 2x^2 + x\) \((+c)\)
AnswerMarks Guidance
\((1,5)\) used to give \(c=5\)B2, 1, 0; B1, ∇ [3] Co - unsimplified ok. Must have integrated + use of \(x=1\) and \(y=5\) for \(c\).
(ii) \(3x^2-4x+1>0\)
\(\rightarrow\) end values of \(1\) and \(\frac{1}{3}\)
AnswerMarks Guidance
\(\rightarrow x<\frac{1}{3}\) and \(x>1\)M1, A1, A1 [3] Set to 0 and attempt to solve. Co for end values – even if "\(>\)" etc. Co (allow \(\leq\) and \(\geq\)). Allow \(1
**(i)** $y = x^3 - 2x^2 + x$ $(+c)$
$(1,5)$ used to give $c=5$ | B2, 1, 0; B1, ∇ [3] | Co - unsimplified ok. Must have integrated + use of $x=1$ and $y=5$ for $c$.

**(ii)** $3x^2-4x+1>0$
$\rightarrow$ end values of $1$ and $\frac{1}{3}$
$\rightarrow x<\frac{1}{3}$ and $x>1$ | M1, A1, A1 [3] | Set to 0 and attempt to solve. Co for end values – even if "$>$" etc. Co (allow $\leq$ and $\geq$). Allow $1<x<\frac{1}{3}$.
4 A curve is such that $\frac { \mathrm { d } y } { \mathrm {~d} x } = 3 x ^ { 2 } - 4 x + 1$. The curve passes through the point $( 1,5 )$.\\
(i) Find the equation of the curve.\\
(ii) Find the set of values of $x$ for which the gradient of the curve is positive.

\hfill \mbox{\textit{CAIE P1 2003 Q4 [6]}}