Marianopolis · Science · 201-SN2-RE

201-SN2-RE Differential Calculus tutoring

Get one-to-one help with limits, derivative rules and calculus applications for Marianopolis Science 201-SN2-RE. Try the short example below, or send a question or topic you want help with.

Your Marianopolis Science calculus course

201-SN2-RE is the Differential Calculus course for Marianopolis Science. Its course description connects limits and continuity with the definition, calculation and applications of derivatives. Bring your current section outline to choose the topics and assessment preparation that apply to you.

If your outline says 201-AS2-MS, use the separate Arts & Sciences guide linked below. Keep the full course code in your request.

Topics to work on

  • Limits, continuity and derivatives from the definition
  • Differentiation methods, indeterminate forms and L’Hôpital’s rule
  • Graphing, optimization and rates of change
  • Linear and higher-order approximations

If L’Hôpital’s rule is among your current topics, try this optional method-choice practice.

Your 201-SN2-RE revision route

Choose only topics listed for your assessment. The course description supports this subject, but does not establish your section’s exam date or chapter cutoff.

  1. Choose topics. Early topics: limits and continuity
  2. Follow a worked example. Follow the product and chain rules
  3. Try without solutions. Try the existing course diagnostic before opening answers
  4. Get help with a step. Ask about 201-SN2-RE tutoring Include the chapter, assessment date and question; attempted work is useful but not required. Sessions are currently in English.

If your assessment includes applications: complete rational-function curve investigation. Otherwise, stay with the limits and derivative rules above.

Official course source Your section outline and instructor announcements take priority. These are Nablio study routes and exercises, not official exams.

A useful starting point

Review inequalities, function composition and the fact that a real logarithm requires a positive input. Try the example after learning the logarithm derivative and chain rule.

Steps worth checking

  • Preserving the original function’s domain after differentiating
  • Keeping the inner derivative in the chain rule

Where did your derivative go wrong?

Use these as topic practice for Science 201-SN2-RE. Your current section outline determines which topics to review.

A 25-minute differential calculus check

Find a limit using a conjugate, use a derivative to locate a maximum, and connect an area rate to a radius rate. Try each question before opening its solution.

Before you start: Allow 18 minutes to try the three questions, then 7 minutes to check and retry one missed step.

1. A limit without a function value

Find lim⁡x→09+x−3x\displaystyle\lim_{x\to0}\frac{\sqrt{9+x}-3}{x}. Explain why substituting zero initially does not give the limit.

Show the explained solution
  1. At x=0x=0, the original quotient is undefined and direct substitution gives the indeterminate form 0/00/0. This does not tell us the limit.
  2. For nearby x≠0x\ne0, multiply by the conjugate and cancel the factor xx: 9+x−3x=19+x+3.\frac{\sqrt{9+x}-3}{x}=\frac{1}{\sqrt{9+x}+3}.
  3. The expression on the right is continuous at zero, so its limit is 1/(3+3)=1/61/(3+3)=1/6. Cancelling for nonzero inputs helps compute the limit; it does not define the original quotient at zero.

Review limits and excluded inputs

2. From a derivative to a maximum

On 0≤x≤30\le x\le3, let f(x)=xe−xf(x)=xe^{-x}. Find where it increases and decreases, and find its absolute maximum.

Show the explained solution
  1. The product rule and chain rule give f′(x)=e−x−xe−x=e−x(1−x)f^{\prime}(x)=e^{-x}-xe^{-x}=e^{-x}(1-x). The factor e−xe^{-x} is always positive.
  2. Therefore f′>0f^{\prime}>0 for 0<x<10<x<1 and f′<0f^{\prime}<0 for 1<x<31<x<3. The function increases up to x=1x=1, then decreases.
  3. Check the interior critical point and both endpoints: f(0)=0f(0)=0, f(1)=1/ef(1)=1/e, and f(3)=3/e3f(3)=3/e^3. The absolute maximum is 1/e1/e at x=1x=1. A zero derivative was a candidate; the sign change and endpoint check establish the result.

Distinguish a local maximum from a global maximum

3. Convert an area rate to a radius rate

A circular patch has area A=πr2A=\pi r^2. Its area is increasing at 6π cm2/s6\pi\,\mathrm{cm^2/s}. How fast is the radius increasing when r=3 cmr=3\,\mathrm{cm}?

Show the explained solution
  1. Both area and radius depend on time. Differentiate the relation before replacing the changing radius by its instantaneous value: dAdt=2πrdrdt.\frac{dA}{dt}=2\pi r\frac{dr}{dt}.
  2. At the stated instant, dr/dt=(6π)/(2π⋅3)=1 cm/sdr/dt=(6\pi)/(2\pi\cdot3)=1\,\mathrm{cm/s}. The positive sign agrees with an expanding patch.
  3. Dividing area per time by a length gives length per time. The area rate is not the radius rate: it is scaled by the current circumference.

Review related rates

Use your answers to plan your revision
  1. If the limit stalled

    Redo the conjugate step, stating which input is excluded. Then try one limit from your assigned review without looking at an example.

  2. If the derivative was right but the conclusion was wrong

    Draw a sign line for the derivative and list all endpoint and critical-point candidates before choosing an extremum.

  3. If units or changing quantities caused trouble

    Name the time-dependent quantities and their units. Differentiate their relation before inserting instantaneous measurements.

For help with 201-SN2-RE, start with a limit, derivative or related-rate question, or a concept you want explained. Your tutor can help you choose the first step or review an attempt with you. Your assessment topic list, if you have it, can help focus the examples.

Request 201-SN2-RE exam preparation help

Original Nablio practice, not an official examination.

Course topic sources

Keep the domain when you differentiate

Let xx be a real variable and g(x)=ln⁡(5−x2)g(x)=\ln(5-x^2), where ln⁡\ln is the natural logarithm. Find the real domain of gg, calculate g′(x)g^{\prime}(x) and state where that derivative applies.

Show a hint

First solve 5−x2>05-x^2>0. Then treat 5−x25-x^2 as the inner function and ln⁡\ln as the outer function.

Show the reasoning
  1. 1. Find the allowed inputs

    The logarithm needs a strictly positive argument: 5−x2>05-x^2>0. This gives x2<5x^2<5, or −5<x<5-\sqrt5<x<\sqrt5. The domain is (−5,5)(-\sqrt5,\sqrt5); the endpoints are excluded because their argument would be zero.

  2. 2. Use the chain rule

    Write u(x)=5−x2u(x)=5-x^2, so u′(x)=−2xu^{\prime}(x)=-2x. The logarithm rule gives g′(x)=u′(x)u(x)=−2x5−x2.g^{\prime}(x)=\frac{u^{\prime}(x)}{u(x)}=\frac{-2x}{5-x^2}. The numerator is the inner derivative; leaving it out would miss how the logarithm’s input changes.

  3. 3. Keep the original domain

    The polynomial 5−x25-x^2 is differentiable everywhere, and the logarithm is differentiable when its argument is positive. Thus g′g^{\prime} exists on exactly (−5,5)(-\sqrt5,\sqrt5). The rational expression can be evaluated at some inputs outside this interval, but those values are not derivatives of the original real function.

A quick check

Substituting x=3x=3 into the rational expression −2x/(5−x2)-2x/(5-x^2) gives 3/23/2. Can you report g′(3)=3/2g^{\prime}(3)=3/2? Explain before opening the answer.

Check your answer

No. The original input would give g(3)=ln⁡(−4)g(3)=\ln(-4), which is not defined as a real number. Since 33 is outside the domain of gg, its real derivative at 3 does not exist. A usable algebraic expression does not extend the original function’s domain.

If the inequality was difficult, review domains before more derivatives. If the domain was right but the numerator was missing, use the derivative-rule check to practise identifying the inner function.

What to work through with a tutor

Bring a question, even if you do not know how to start. A tutor can help compare one-sided limits, test continuity, or separate the inner and outer functions before you differentiate.

For graphing, optimization or an approximation, your tutor can help connect the formula to the question: define the allowed inputs, choose the method and explain what the result means. If you have started a solution, your tutor can use it to identify the next skill to practise.

Prepare from your own course outline

Start with the topic list and instructions from your current section. Sort missed questions into domain or algebra errors, rule-selection errors and interpretation errors. Redo one from each relevant group, explaining why the method applies. Include L’Hôpital’s rule or approximations when they are part of your assigned review.

Course information

Before requesting a lesson

Is this the Arts & Sciences calculus course?

No. This page is for Science 201-SN2-RE. Arts & Sciences uses 201-AS2-MS. Topics overlap, but use the code and instructions on your own outline.

What should I send with my request?

Send Marianopolis 201-SN2-RE, the topic you want help with and your preferred times. You can add your current outline, a question you are allowed to share and any work you have started. Start with a problem you’re stuck on or an unclear concept; your tutor can help you work from the basics and build confidence. We confirm whether we can help, availability, lesson details and price before payment.

Are lessons available in French?

This guide is available in English and French. Tutoring sessions are currently in English, online through Zoom or Google Meet.

Is Nablio part of Marianopolis?

Nablio provides independent tutoring and is not affiliated with or endorsed by Marianopolis College.

Ask for help with your question

Send your topic or question. Include your full course code if you have it. You can ask for help with the first step or share any work you have started.

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