OCR MEI C3 — Question 2 4 marks

Exam BoardOCR MEI
ModuleC3 (Core Mathematics 3)
Marks4
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicComposite & Inverse Functions
TypeFind composite function expression
DifficultyModerate -0.8 This question requires straightforward function composition and testing for odd/even properties using definitions. The compositions ln(1+x²) and 1+(ln x)² are direct substitutions, and checking odd/even involves routine algebraic verification of f(-x) vs f(x). It's simpler than average A-level questions as it requires only basic recall and application of definitions with no problem-solving or multi-step reasoning.
Spec1.02u Functions: definition and vocabulary (domain, range, mapping)1.02v Inverse and composite functions: graphs and conditions for existence

The functions f(x) and g(x) are defined as follows. $$\text{f}(x) = \ln x, \quad x > 0$$ $$\text{g}(x) = 1 + x^2, \quad x \in \mathbb{R}$$ Write down the functions fg(x) and gf(x), and state whether these functions are odd, even or neither. [4]

Question 2:
AnswerMarks
2fg(x) = ln(1+x2) (x  )
gf(x) = 1+(ln x)2 (x > 0)
ln(1+x2) even
AnswerMarks
1 + (lnx)2 neitherB1
B1
B1
B1
AnswerMarks
[4]condone missing bracket, and
missing or incorrect domains
Penalise missing bracket
AnswerMarks
Penalise missing bracketIf fg and gf the wrong way round, B1B0
not 1 + ln(x2)
Question 2:
2 | fg(x) = ln(1+x2) (x  )
gf(x) = 1+(ln x)2 (x > 0)
ln(1+x2) even
1 + (lnx)2 neither | B1
B1
B1
B1
[4] | condone missing bracket, and
missing or incorrect domains
Penalise missing bracket
Penalise missing bracket | If fg and gf the wrong way round, B1B0
not 1 + ln(x2)
The functions f(x) and g(x) are defined as follows.
$$\text{f}(x) = \ln x, \quad x > 0$$
$$\text{g}(x) = 1 + x^2, \quad x \in \mathbb{R}$$

Write down the functions fg(x) and gf(x), and state whether these functions are odd, even or neither. [4]

\hfill \mbox{\textit{OCR MEI C3  Q2 [4]}}