Vanier · Science · 201-SN2-RE

201-SN2-RE Differential Calculus tutoring

Turn a calculus question into a clear sequence: define the function, choose the derivative rule and explain the result. Start with a short optimization check for Vanier Science calculus.

Your Vanier differential calculus course

Vanier’s Pure and Applied Science course list places 201-SN2-RE Differential Calculus in semester 1. The course develops limits, continuity and derivatives, including trigonometric, exponential and logarithmic functions, with applications to graphing, related rates and optimization.

Vanier lists Social Science Calculus 1 separately as 201-107-VA. Use the full code on your outline when requesting help.

Topics to work on

  • Limits and continuity
  • Derivatives of algebraic, trigonometric, exponential and logarithmic functions
  • Graphs and rates of change
  • Related rates and optimization

Before you start

Review factoring, function notation and the product and chain rules. For an application, write the permitted values of the variable before solving the derivative equation.

Choose a starting point

Differential calculus: implicit slopes and turning points

Differentiate an implicit equation, then use a derivative sign chart to classify stationary points.

Before you start: Allow 20–25 minutes to try both questions, then 15 minutes to check and retry any missed steps.

1. A slope on an implicit curve

On the curve x2+xy+y2=7x^2+xy+y^2=7, find dy/dxdy/dx at (1,2)(1,2). Check that the point belongs to the curve.

Show the explained solution
  1. The point satisfies 1+2+4=71+2+4=7. Treat yy as a function of xx.
  2. Differentiation gives 2x+y+xy′+2yy′=02x+y+xy^\prime+2yy^\prime=0. In particular, the derivative of xyxy needs both product-rule terms.
  3. y′=−2x+yx+2y.y^\prime=-\frac{2x+y}{x+2y}. At (1,2)(1,2), the slope is −4/5-4/5.

Review implicit differentiation step by step

2. Classify stationary points

For h(x)=x3−3x2+2h(x)=x^3-3x^2+2, find the stationary points and classify them using the sign of h′h^\prime.

Show the explained solution
  1. h′(x)=3x(x−2)h^\prime(x)=3x(x-2), so the stationary inputs are x=0x=0 and x=2x=2.
  2. The derivative is positive for x<0x<0, negative for 0<x<20<x<2, and positive for x>2x>2.
  3. Therefore (0,2)(0,2) is a local maximum and (2,−2)(2,-2) a local minimum. They are not global extrema on the whole real line.

Use derivative signs to classify an extremum

Use your answers to plan your revision
  1. Implicit differentiation

    Underline every occurrence of the dependent variable. Explain where each factor of its derivative comes from.

  2. Classification

    Make a sign table before using the words maximum or minimum; identify whether your conclusion is local or global.

For Vanier calculus help, send the rule or sign-chart step you could not explain. Keep your section’s outline beside the practice so the review matches your assessment.

Request 201-SN2-RE exam preparation help

Original Nablio practice, not an official examination.

Course topic sources

Which cut makes the largest open box?

A square sheet of card is 24 cm on each side. Cut a square of side xx cm from each corner, then fold up the sides to make an open-top box. Ignore the thickness of the card. Write the volume V(x)V(x), state the physical domain (the allowed values of xx that make a box) and find the cut that gives the largest volume.

Show a hint

The box height is xx. Each base side loses a length xx at both ends, so it becomes 24−2x24-2x.

Show the reasoning
  1. 1. Name the dimensions and domain

    The height is xx cm and each base side is 24−2x24-2x cm. A box must have a positive height and a positive base side, so 0<x<12.0<x<12.

    Volume is height times base area: V(x)=x(24−2x)2.V(x)=x(24-2x)^2. Here VV is measured in cubic centimetres.

  2. 2. Differentiate both factors

    The function is a product of xx and (24−2x)2(24-2x)^2. Apply the product rule, and use the chain rule on the square: V′(x)=(24−2x)2−4x(24−2x)=(24−2x)(24−6x).\begin{gathered}V^\prime(x)=(24-2x)^2\\\quad-4x(24-2x)\\=(24-2x)(24-6x).\end{gathered}

    The factor −4-4 comes from 2(24−2x)2(24-2x) multiplied by the inner derivative −2-2. Keeping only (24−2x)2(24-2x)^2 would omit the change in the base area.

  3. 3. Check the candidates against the domain

    The equation V′(x)=0V^\prime(x)=0 gives x=12x=12 or x=4x=4. The value x=12x=12 makes the base side zero and lies outside 0<x<120<x<12. The only interior candidate is x=4x=4.

  4. 4. Show why it is a maximum

    Within 0<x<120<x<12, the factor 24−2x24-2x is positive. The other factor, 24−6x24-6x, is positive for 0<x<40<x<4 and negative for 4<x<124<x<12. Thus the volume increases up to x=4x=4 and decreases after it.

    This sign change establishes the maximum over the physical domain. Solving the derivative equation alone would only identify candidates.

  5. 5. State the dimensions and volume

    Cut out 4 cm squares. The resulting box has height 4 cm and base dimensions 16×1616\times16 cm. Its maximum volume is V(4)=4(24−8)2=1024 cm3.\begin{aligned}V(4)&=4(24-8)^2\\&=1024\text{ cm}^3.\end{aligned} A length answer of 4 cm and a volume answer of 1024 cm³ describe different quantities.

Your turn

For the same construction using a square card with side length L>0L>0, the volume is V(x)=x(L−2x)2V(x)=x(L-2x)^2. What cut gives the maximum? Identify the domain and explain which derivative root must be excluded.

Check your answer

The domain is 0<x<L/20<x<L/2 and V′(x)=(L−2x)(L−6x)V^\prime(x)=(L-2x)(L-6x). The root x=L/2x=L/2 collapses the base; the interior root is x=L/6x=L/6. The derivative is positive before L/6L/6 and negative afterward, so that cut maximizes the volume. For L=24L=24, this returns x=4x=4.

If the dimensions were wrong, sketch the sheet and label both corner cuts on one edge. If the model was right but the derivative was wrong, work through the derivative-rule check before trying another application.

What to work through with a tutor

Your tutor can help you set up the problem or review what you have started, label the variables with you and check which values make sense in the situation.

Your tutor can help you choose the first derivative rule and explain each product, quotient or chain-rule step. If you have already tried the derivative, you can look together for a missing factor or step.

Your tutor can check your derivative sign analysis with you, help you justify a maximum or minimum and connect the answer to the problem’s quantities and units.

Build a mixed practice set

Pair a limit or continuity question with a derivative-rule question and one application from your outline. For every optimization problem, write the domain, find the candidates and justify the maximum or minimum. Redo the setup without the solution before changing the numbers.

Official course information

Lesson questions

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Bring your current course outline and a question you are allowed to share, if you have them. Any work you have started is useful, but you can also ask for help with the first step. Your outline helps us choose topics that match your section and follow its assessment rules.

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