IB Questionbank

Updates to Questionbank

User interface language: English | Español

Date	May 2021	Marks available	2	Reference code	21M.2.SL.TZ1.9
Level	Standard Level	Paper	Paper 2	Time zone	Time zone 1
Command term	Find	Question number	9	Adapted from	N/A

Question

Consider the function $f$ defined by $f (x) = 90 e^{- 0.5 x}$ for $x \in ℝ^{+}$ .

The graph of $f$ and the line $y = x$ intersect at point $P$ .

The line $L$ has a gradient of $- 1$ and is a tangent to the graph of $f$ at the point $Q$ .

The shaded region $A$ is enclosed by the graph of $f$ and the lines $y = x$ and $L$ .

Find the $x$ -coordinate of $P$ .

[2]

a.

Find the exact coordinates of $Q$ .

[4]

b.

Show that the equation of $L$ is $y = - x + 2 \ln 45 + 2$ .

[2]

c.

Find the $x$ -coordinate of the point where $L$ intersects the line $y = x$ .

[1]

d.i.

Hence, find the area of $A$ .

[4]

d.ii.

The line $L$ is tangent to the graphs of both $f$ and the inverse function $f^{- 1}$ .

Find the shaded area enclosed by the graphs of $f$ and $f^{- 1}$ and the line $L$ .

[2]

e.

Markscheme

Attempt to find the point of intersection of the graph of $f$ and the line $y = x$ (M1)

$x = 5.56619 \dots$

$= 5.57$ A1

[2 marks]

a.

$f' (x) = - 45 e^{- 0.5 x}$ A1

attempt to set the gradient of $f$ equal to $- 1$ (M1)

$- 45 e^{- 0.5 x} = -1$

$Q$ has coordinates $(2 \ln 45, 2)$ (accept ( $- 2 \ln \frac{1}{45}, 2$ ) A1A1

Note: Award A1 for each value, even if the answer is not given as a coordinate pair.

Do not accept $\frac{\ln \frac{1}{45}}{- 0.5}$ or $\frac{\ln 45}{0.5}$ as a final value for $x$ . Do not accept $2.0$ or $2.00$ as a final value for $y$ .

[4 marks]

b.

attempt to substitute coordinates of $Q$ (in any order) into an appropriate equation (M1)

$y - 2 = - (x - 2 \ln 45)$ OR $2 = - 2 \ln 45 + c$ A1

equation of $L$ is $y = - x + 2 \ln 45 + 2$ AG

[2 marks]

c.

$x = \ln 45 + 1 (= 4.81)$ A1

[1 mark]

d.i.

appropriate method to find the sum of two areas using integrals of the difference of two functions (M1)

Note: Allow absence of incorrect limits.

$\int_{4.806 \dots}^{5.566 \dots} (x - (- x + 2 \ln 45 + 2)) d x + \int_{5.566 \dots}^{7.613 \dots} (90 e^{- 0.5 x} - (- x + 2 \ln 45 + 2)) d x$ (A1)(A1)

Note: Award A1 for one correct integral expression including correct limits and integrand.
Award A1 for a second correct integral expression including correct limits and integrand.

$= 1.52196 \dots$

$= 1.52$ A1

[4 marks]

d.ii.

by symmetry $2 \times 1.52 \dots$ (M1)

$= 3.04$ A1

Note: Accept any answer that rounds to $3.0$ (but do not accept $3$ ).

[2 marks]

e.

Examiners report

[N/A]

a.

[N/A]

b.

[N/A]

c.

[N/A]

d.i.

[N/A]

d.ii.

[N/A]

e.

Syllabus sections

Topic 2—Functions » SL 2.2—Functions, notation domain, range and inverse as reflection

Show 83 related questions

22M.1.SL.TZ2.1a:
Find $g (0)$ .
22M.1.SL.TZ2.1c:
Find the value of $x$ such that $f (x) = 0$ .
18N.2.AHL.TZ0.H_9c.i:
sketch the graph of $y = f\left( x \right)$ , showing clearly any axis intercepts and giving the equations of any asymptotes.
21N.1.AHL.TZ0.2a.i:
the vertical asymptote of the graph of $f$ .
21N.1.AHL.TZ0.2a.ii:
the horizontal asymptote of the graph of $f$ .
21N.1.AHL.TZ0.2c:
Sketch the graph of $f$ on the axes below.
18M.1.SL.TZ1.T_15b:
Write down the x-coordinate of P and the x-coordinate of Q.
19M.2.SL.TZ2.T_5b:
Write down the $y$ -intercept of the graph of $y = f\left( x \right)$ .
19M.2.AHL.TZ1.H_4a:
Write down the range of $f$ .
17M.1.AHL.TZ2.H_2a:
Write down the range of $f$ .
16N.2.AHL.TZ0.H_5c:
Solve the inequality $\left| {3x\arccos (x)} \right| > 1$ .
17M.1.SL.TZ1.T_12b.ii:
Write down the number of solutions to $f(x) = - 6$ .
17M.2.AHL.TZ1.H_12c:
Explain why $f$ is an even function.
19N.1.SL.TZ0.S_10c:
The line ${L_2}$ is tangent to the graph of $g$ at ${\text{A}}$ and has equation $y = \left( {{\text{ln}}\,p} \right)x + q + 1$ .

The line ${L_2}$ passes through the point $\left( { - 2{\text{, }} - 2} \right)$ .

The gradient of the normal to $g$ at ${\text{A}}$ is $\frac{1}{{{\text{ln}}\left( {\frac{1}{3}} \right)}}$ .

Find the equation of ${L_1}$ in terms of $x$ .
18M.1.SL.TZ1.T_15c:
Write down the values of x for which $f\left( x \right) > g\left( x \right)$ .
21N.1.AHL.TZ0.2b.ii:
the $y$ -axis.
19M.2.SL.TZ1.T_4a:
Find the value of $f\left( x \right)$ when $x = \frac{1}{2}$ .
17M.2.AHL.TZ1.H_12b:
Sketch the graph of $y = f(x)$ showing clearly the equations of asymptotes and the coordinates of any intercepts with the axes.
19N.1.SL.TZ0.S_10a:
Write down the coordinates of ${\text{B}}$ .
18N.2.AHL.TZ0.H_9c.ii:
sketch the graph of $y = {f^{ - 1}}\left( x \right)$ , showing clearly any axis intercepts and giving the equations of any asymptotes.
19M.2.SL.TZ2.T_5c:
Sketch the graph of $y = f\left( x \right)$ for −3 ≤ $x$ ≤ 3 and −4 ≤ $y$ ≤ 12.
19N.2.AHL.TZ0.H_3b:
Given that ${f^{ - 1}}\left( a \right) = 3$ , determine the value of $a$ .
17M.1.AHL.TZ2.H_2b:
Find an expression for ${f^{ - 1}}(x)$ .
EXN.1.SL.TZ0.8c:
Find an expression for $f^{- 1} (x)$ , stating its domain.
22M.1.AHL.TZ2.6b:
The range of $f$ is $a \leq y \leq b$ , where $a, b \in ℝ$ .

Find the value of $a$ and the value of $b$ .
17M.2.SL.TZ2.S_3a:
Write down the range of $f$ .
22M.2.AHL.TZ1.10b.ii:
State the domain and range of $f^{- 1}$ .
22M.2.AHL.TZ2.10a.ii:
Plant $A$ correct to three significant figures.
19N.2.AHL.TZ0.H_3c:
Given that $g\left( x \right) = 2f\left( {x - 1} \right)$ , find the domain and range of $g$ .
20N.1.AHL.TZ0.H_10a.i:
Write down an expression for $f' (x)$ .
20N.1.AHL.TZ0.H_10b.i:
Show that $g^{- 1}$ exists.
20N.1.AHL.TZ0.H_12b:
State the equation of the horizontal asymptote on the graph of $y = f (x)$ .
20N.1.AHL.TZ0.H_12d:
Sketch the graph of $y = f (x)$ , stating clearly the equations of any asymptotes and the coordinates of any points of intersections with the coordinate axes.
20N.1.SL.TZ0.T_2a.ii:
State, in the context of the question, what the value of $8.50$ represents.
20N.1.SL.TZ0.T_2b:
Write down the minimum number of pizzas that can be ordered.
19N.2.AHL.TZ0.H_3a:
Find the value of $\left( {f \circ f} \right)\left( 1 \right)$ .
18M.1.SL.TZ1.T_15a:
Find the range of f.
18N.2.AHL.TZ0.H_9d:
Hence, or otherwise, solve the inequality $f\left( x \right) > {f^{ - 1}}\left( x \right)$ .
16N.2.AHL.TZ0.H_5b:
State the range of $f$ .
17M.2.AHL.TZ1.H_12d:
Explain why the inverse function ${f^{ - 1}}$ does not exist.
17M.2.AHL.TZ1.H_12g.i:
Hence, show that there are no solutions to $g'(x) = 0$ ;
20N.1.AHL.TZ0.H_10b.iii:
Hence find $g^{- 1} (x)$ .
20N.1.AHL.TZ0.H_10a.ii:
Hence, given that $f^{- 1}$ does not exist, show that $b^{2} - 3 a c > 0$ .
17M.2.AHL.TZ1.H_12a:
Find the largest possible domain $D$ for $f$ to be a function.
17M.2.AHL.TZ1.H_12f:
Find $g'(x)$ .
16N.2.AHL.TZ0.H_5a:
Sketch the graph of $f$ indicating clearly any intercepts with the axes and the coordinates of any local maximum or minimum points.
17M.1.SL.TZ1.T_12b.i:
Draw the line $y = - 6$ on the axes.
19N.1.SL.TZ0.S_10b:
Given that $f'\left( a \right) = \frac{1}{{{\text{ln}}\,p}}$ , find the equation of ${L_1}$ in terms of $x$ , $p$ and $q$ .
EXN.1.SL.TZ0.8b:
State the range of $f$ .
17M.2.AHL.TZ1.H_12e:
Find the inverse function ${g^{ - 1}}$ and state its domain.
21M.2.SL.TZ2.5a:
Find the range of $f$ .
17M.2.SL.TZ2.S_3c:
Write down the domain of $g$ .
21N.1.AHL.TZ0.2d:
The function $g$ is defined by $g (x) = \frac{a x + 4}{3 - x}$ , where $x \in ℝ, x \neq 3$ and $a \in ℝ$ .

Given that $g (x) = g^{- 1} (x)$ , determine the value of $a$ .
22M.1.AHL.TZ2.11a:
Sketch the curve $y = f (x)$ , clearly indicating any asymptotes with their equations. State the coordinates of any local maximum or minimum points and any points of intersection with the coordinate axes.
22M.2.AHL.TZ2.10a.i:
Plant $B$ .
21N.1.AHL.TZ0.2b.i:
the $x$ -axis.
16N.1.SL.TZ0.T_9b:
Find the value of $b$ .
16N.1.SL.TZ0.T_9c:
Write down the range of $f(x)$ .
17M.1.SL.TZ1.T_12c:
Find the range of values of $k$ for which $f(x) = k$ has no solution.
20N.1.AHL.TZ0.H_10b.ii:
$g (x)$ can be written in the form $p (x - 2)^{3} + q$ , where $p, q \in ℝ$ .

Find the value of $p$ and the value of $q$ .
20N.1.AHL.TZ0.H_10d:
Sketch the graphs of $y = g (x)$ and $y = g^{- 1} (x)$ on the same set of axes, indicating the points where each graph crosses the coordinate axes.
20N.1.AHL.TZ0.H_12a:
State the equation of the vertical asymptote on the graph of $y = f (x)$ .
20N.1.AHL.TZ0.H_12c:
Use an algebraic method to determine whether $f$ is a self-inverse function.
20N.1.AHL.TZ0.H_12e:
The region bounded by the $x$ -axis, the curve $y = f (x)$ , and the lines $x = 5$ and $x = 7$ is rotated through $2 π$ about the $x$ -axis. Find the volume of the solid generated, giving your answer in the form $π (a + b \ln 2)$ , where $a, b \in ℤ$ .
17M.2.AHL.TZ1.H_12g.ii:
Hence, show that there are no solutions to $({g^{ - 1}})'(x) = 0$ .
17N.2.AHL.TZ0.H_10d:
This region is now rotated through $2\pi$ radians about the $x$ -axis. Find the volume of revolution.
19M.2.AHL.TZ1.H_4b:
Find $f'\left( x \right)$ , stating its domain.
21M.2.AHL.TZ2.12e:
State the domain of $g^{- 1}$ .
20N.1.AHL.TZ0.H_10c:
State each of the transformations in the order in which they are applied.
17N.1.SL.TZ0.S_3c:
On the grid, sketch the graph of ${f^{ - 1}}$ .
EXN.1.SL.TZ0.8d:
Find the coordinates of the point(s) where the graphs of $y = f (x)$ and $y = f^{- 1} (x)$ intersect.
18N.2.AHL.TZ0.H_9b:
Hence, or otherwise, find the coordinates of the point of inflexion on the graph of $y = f\left( x \right)$ .
17M.1.AHL.TZ2.H_2c:
Write down the domain and range of ${f^{ - 1}}$ .
17M.2.SL.TZ1.S_10a.iii:
Write down the value of $k$ .
16N.1.SL.TZ0.T_9a:
Write down the equation of the axis of symmetry for this graph.
19M.2.SL.TZ1.T_4d:
Find the distance from the centre of Orangeton to the point at which the road meets the highway.
19M.2.SL.TZ1.T_4c:
Find the coordinates of the bridges relative to the centre of Orangeton.
20N.1.SL.TZ0.T_2a.i:
State, in the context of the question, what the value of $34.50$ represents.
19M.2.SL.TZ1.T_4e:
This straight road crosses the highway and then carries on due north.

State whether the straight road will ever cross the river. Justify your answer.
20N.1.SL.TZ0.T_2c:
Kaelani has $450 PGK$ .

Find the maximum number of large cheese pizzas that Kaelani can order from Olava’s Pizza Company.
19M.2.SL.TZ1.T_4b.ii:
State the domain of $P$ .
19M.2.SL.TZ2.T_5h:
Determine the range of $f\left( x \right)$ for $p$ ≤ $x$ ≤ $q$ .
19M.2.SL.TZ1.T_4b.i:
Find the function, $P\left( x \right)$ , that would define this footpath on the map.

Hide related questions

Topic 2—Functions