VCAA Mathematical Methods Calculus
15 sample questions with marking guides and sample answers · Avg. score: 58.5%
Substitutions for are used to estimate the limit of as . Which sequence is the most appropriate?
Reveal Answer
This sequence is appropriate because the magnitude of the values decreases (), meaning is getting progressively closer to .
This sequence is incorrect because the values are moving away from (), which does not help estimate the limit as .
This sequence includes , where the expression is undefined (division by zero), and subsequent terms move away from .
This sequence consists of increasing integers moving away from , which would be used to investigate the limit as , not as .
A horizontal point of inflection is a point of inflection that is also a stationary point.
Determine the value/s of for which the graph of has only one horizontal point of inflection.
Reveal Answer
Stationary points
(i)
The quadratic has real roots when discriminant
There is only ONE phi
(not valid)
and so
Sub into (i) to determine the x-ordinate of the stationary point.
For
For
For each value, is the x-ordinate of both a stationary point () and a point of inflection ()
There is a point of horizontal inflection at when
| Descriptor | Marks |
|---|---|
correctly determines the first derivative | 1 |
correctly determines the quadratic equation to identify the stationary point/s | 1 |
determines valid and non-valid solutions of k | 1 |
determines x-ordinate of stationary point | 1 |
determines values of second derivative for both values of k | 1 |
shows logical organisation communicating key steps | 1 |
At the point where , the tangent to the circle given by the equation meets the positive direction of the -axis at an angle of .
The value of could be
0
Reveal Answer
The circle's domain is , so is outside the circle and cannot be a point of tangency.
At , the tangent line to the circle is vertical, meaning its slope is undefined rather than .
The tangent's slope is . Using implicit differentiation, gives . Substituting this into the circle equation yields , so .
This value would correspond to a different tangent slope, likely resulting from using an incorrect angle such as or .
0
At , the tangent lines to the circle are horizontal (slope of 0), which corresponds to an angle of or , not .
Let , and , .
Find all real values of , such that is the absolute maximum value of .
Reveal Answer
This option only includes the points where reaches the global maximum of , which is . It misses the intervals where is a local maximum that remains the absolute maximum on the restricted interval .
This incorrectly assumes can be any value between the critical points. For , the shifted interval will contain values of where , meaning is not the maximum.
This option incorrectly includes . For these values, , and the function is strictly increasing immediately to the right of , so cannot be the maximum on .
This incorrectly includes . For these negative values of , the function increases as moves to the right of , meaning will exceed on the interval .
To make the maximum on , must either be in the region where is strictly decreasing (), or must be on the decreasing slope such that the right endpoint doesn't exceed , requiring .
The derivative of the function is given by . It is known that .
Determine .
Reveal Answer
This option fails to apply the reverse chain rule (u-substitution). The integral of is , so you must divide by the coefficient .
This option uses the wrong sign for the antiderivative and misses the chain rule factor. The integral of is , not , and the result must be divided by .
Integrating yields . Using the condition , we solve to find .
This option has the wrong sign for the cosine term. Since the derivative of is , the antiderivative of must be negative.
State the trapezoidal rule and use it with six strips to determine an approximate value of the definite integral for the curve of from to . Show all substitutions made into the rule.
Reveal Answer
| Descriptor | Marks |
|---|---|
Correctly determines the rectangle width | 1 |
Correctly states the trapezoidal rule | 1 |
Substitutes appropriate values into the trapezoidal rule | 1 |
Determines the approximate value of the definite integral | 1 |
A function has the derivative .
Given that , the value of is
2
3
5
7
Reveal Answer
2
Incorrect. Evaluating the antiderivative at yields 7, not 2.
3
Incorrect. This might result from ignoring the constant of integration and calculating , then making an arithmetic error.
5
Incorrect. This is the value of the initial condition , not the requested value .
7
Correct. Integrating gives . Substituting gives , and evaluating yields .
Let be the probability density function for a continuous random variable , where
and is a positive real number.
The value of is
Reveal Answer
Incorrect. This value does not make the total area under the probability density function equal to 1, likely resulting from an error in evaluating the trigonometric integrals.
Correct. For to be a valid probability density function, its integral over all must equal 1. Evaluating yields , which gives .
Incorrect. This might result from incorrectly rationalizing the denominator or making an arithmetic error when solving .
Incorrect. This is the value of the integral when . Since the total area must be 1, must be the reciprocal of this value.
A community group that uses social media created a new post on the internet on a day when they had 1000 members. The rate of change in their number of members (members/day) is given by , where represents days after the new post.
Determine the time it will take for the community group to achieve seven times the initial number of members. Express your answer in the form .
Reveal Answer
7 times the members is 7000.
Let m be the time when 7000 members is reached.
The required change in members is 6000.
| Descriptor | Marks |
|---|---|
Correctly uses the initial conditions to determine the increase | 1 |
Correctly determines the integral | 1 |
Determines the number of days required | 1 |
The gradient of the graph of at the point where the graph crosses the vertical axis is equal to
Reveal Answer
Incorrect. This might result from confusing the x-coordinate of the y-intercept () with the gradient itself.
Incorrect. This value does not match the derivative evaluated at the y-intercept.
Incorrect. This is the y-coordinate of the y-intercept (), not the gradient. It could also result from forgetting the chain rule and incorrectly assuming the derivative is .
Incorrect. This value does not correspond to the derivative evaluated at .
Correct. The gradient is found using the derivative . The graph crosses the vertical axis at , so evaluating the derivative gives .
The number of koalas in a conservation park is modelled by , , where represents the time (years) since the park opened. There were 20 koalas in the park when it opened.
Determine the approximate rate of change in the number of koalas when .
46
26
25
5
Reveal Answer
46
This is the value of the function . This represents the number of koalas (or the population increase) at year 3, rather than the rate at which the population is changing.
26
This value appears to be the result of calculating . This subtracts the initial population from the model's value at , which does not represent the instantaneous rate of change.
25
This is an incorrect value. It does not correspond to the derivative at or the function value, likely resulting from a calculation error.
5
The rate of change is found by taking the derivative . Using the chain rule, . Evaluating at gives , which rounds to 5.
The derivative of a function is given by .
Determine the interval on which the graph of is both decreasing and concave up.
Reveal Answer
The function is decreasing when and concave up when
when
when
Therefore, the function is decreasing and concave up when
| Descriptor | Marks |
|---|---|
correctly describes conditions when the function is decreasing and concave up | 1 |
correctly determines the interval where f(x) is decreasing | 1 |
correctly determines the interval where f(x) is concave up | 1 |
determines interval when function is decreasing and concave up | 1 |
The maximum value of the function is
0
1
2
Reveal Answer
This is the minimum value of the function on the interval, which occurs at the critical point since .
0
To find the maximum, we evaluate at the critical point and endpoints . Comparing , , and , the maximum value is .
1
This is the -value of the critical point (found by setting ), not the maximum value of the function itself.
2
This is the -value at which the maximum occurs, but the question asks for the maximum value of the function, which is .
This value does not correspond to the function evaluated at any critical point or endpoint within the given interval .
Determine
Reveal Answer
Correct. Using the power rule for integration, we increase the exponent by 1 and divide the coefficient by the new exponent: .
Incorrect. This option incorrectly subtracts the new exponent (4) from the coefficient 10.4 instead of dividing by it.
Incorrect. This option incorrectly adds the new exponent (4) to the coefficient 10.4 instead of dividing by it.
Incorrect. This option incorrectly multiplies the coefficient 10.4 by the new exponent (4) instead of dividing by it, confusing the integration rule with the differentiation rule.
The rate that water fills an empty vessel is given by (in litres per hour), , where is time (in hours).
Determine the function that represents the volume of water in the vessel (in litres).
Reveal Answer
when
| Descriptor | Marks |
|---|---|
correctly determines the integral of the function V(t) | 1 |
determines the value of c | 1 |
The vessel is full when . Determine the volume of water, to the nearest litre, the vessel can hold when full.
Reveal Answer
litres
| Descriptor | Marks |
|---|---|
determines the simplified exponential term | 1 |
determines number of litres | 1 |
Use information from the table and the trapezoidal rule to determine the approximate volume of water in the vessel after three hours.
| 0 | 0.25 |
| 1 | 0.32 |
| 2 | 0.41 |
| 3 | 0.53 |
Reveal Answer
Using trapezoidal rule
Volume after 3 hours
Volume after 3 hours litres
| Descriptor | Marks |
|---|---|
establishes expression for approximate number of litres of water in vessel after 3 hours | 1 |
determines approximate number of litres | 1 |