OCR MEI C2 — Question 5 3 marks

Exam BoardOCR MEI
ModuleC2 (Core Mathematics 2)
Marks3
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicTangents, normals and gradients
TypeIncreasing/decreasing intervals
DifficultyModerate -0.8 This is a straightforward application of differentiation to find where a function is decreasing. Students need only differentiate x² - 7x to get 2x - 7, set it less than zero, and solve to get x < 3.5. This is simpler than average A-level questions as it requires just one standard technique with no problem-solving or multi-step reasoning.
Spec1.07o Increasing/decreasing: functions using sign of dy/dx
Find the set of values of \(x\) for which \(x^2 - 7x\) is a decreasing function. [3]
Question 5:
AnswerMarks
5dy
2x7 or (x-3.5)2 [– 3.52]
dx
x = 3.5
AnswerMarks
x < 3.5 www caoM1
M1
A1
AnswerMarks
[3]M2 for x = 3.5 identified (for example, from
symmetry)
AnswerMarks
allow x ≤ 3.5mark the final answer 
Question 5:
5 | dy
2x7 or (x-3.5)2 [– 3.52]
dx
x = 3.5
x < 3.5 www cao | M1
M1
A1
[3] | M2 for x = 3.5 identified (for example, from
symmetry)
allow x ≤ 3.5 | mark the final answer
Find the set of values of $x$ for which $x^2 - 7x$ is a decreasing function. [3]

\hfill \mbox{\textit{OCR MEI C2  Q5 [3]}}
This paper (11 questions)
View full paper
Q1 4 Q2 5 Q3 3 Q4 4 Q5 3 Q6 2 Q7 12 Q8 2 Q9 5 Q10 3 Q11 4