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Perplex
Perplex
  • Dashboard
Topics
Exponents & LogarithmsRounding & ErrorSequences & SeriesFinancial MathematicsMatricesComplex Numbers
Cartesian plane & linesFunction TheoryModellingTransformations & asymptotes
2D & 3D GeometryVoronoi DiagramsTrig equations & identitiesVectorsGraph Theory
ProbabilityDescriptive StatisticsBivariate StatisticsDistributions & Random VariablesInference & Hypotheses
DifferentiationIntegrationDifferential Equations
Paper 3
Plus
Calculator Skills
Review VideosFormula BookletAll Study Sets
BlogLanding Page
Sign UpLogin
Perplex
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Differentiation
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Limits and Derivatives
Differentiation rules
Limits and Derivatives
Differentiation

Limits and Derivatives

0 of 0 exercises completed

The basic idea of a limit ​x→alim​f(x)​ from tables and graphs, slope as a limit, rate of change and gradient, derivatives of ​xn, and linearity for sums and scalar multiples.

Want a deeper conceptual understanding? Try our interactive lesson!

Basic concept of a limit
SL 5.1

The limit ​x→alim​f(x)​ is the value ​f(x)​ approaches as ​x​ approaches ​a.

Slope as a Limit
SL 5.1

The IB may test your understanding of the gradient of the curve as the limit of

​
m=x2​−x1​y2​−y1​​
​

as ​(x2​−x1​)​ goes to zero.


Limit from a graph
SL 5.1
​
x→1lim​f(x)=2
​
​
x→∞lim​f(x)=23​
​
​
x→−∞lim​f(x)=23​
​

One way to conceptualize a limit is that in the graph above, we can get as close to an output of ​2​ as we want near ​x=1.


Focus on the right side of the curve as it approaches the hole, we could find an ​x​ so that ​1.9<f(x)<2,  ​1.99<f(x)<2,​ or even ​1.9999<f(x)<2.


The key idea here is that since ​x→1lim​f(x)=2, pick a value as close to ​2​ as you want, and we can find an ​x​-value close enough to ​1​ so that ​f(x)​ is even closer to ​2:

Limit from a table
SL 5.1

Given a table of values:

​
xf(x)​0.91.62​0.991.9121​0.9991.9972201​……​
​


​
x→1lim​f(x)=2
​
Gradient
SL 5.1

For a curve ​y=f(x),  ​f′(x)​ is the function that tells you the slope of ​f(x)​ at a certain ​x​ coordinate.

Graphing a derivative with a GDC
SL 5.1

You can graph ​f′(x)​ using the following steps:

  • Press the Y= key.

  • In one of the available function lines (e.g. Y_1), enter the expression for ​f(x).

  • In another available line (e.g. Y_2), input the derivative function usingMATH then 8:nDeriv( in the following format:

    ​
    dXd​(Y1​(x))∣X=X​
    ​


  • To enter ​Y1​, press VARS then scroll to Y-VARS and select FUNCTION then ​Y1​.

  • Press GRAPH to display both the original graph ​f​ and the derivative ​f′.

  • The graph of ​f′​ may take a little bit longer depending on the original function.

After graphing ​f′, you may use all the other graphing functions on the calculator (intersect, zero, and value).

Rate of Change
SL 5.1

​dxdy​​ is the rate of change of ​y​ with respect to ​x​. That is, ​dxdy​​ tells us how much ​y​ changes in response to a change in ​x.


If ​y=f(x), then ​dxdy​=f′(x).

Derivative of xⁿ where n is an integer
SL 5.3
​
f(x)=xn, n∈Z⇒f′(x)=nxn−1📖
​
Derivatives of sums and scalar multiples
SL 5.3
​
dxd​(af(x))=af′(x)🚫
​
​
dxd​(f(x)+g(x))=f′(x)+g′(x)🚫
​
​
dxd​(af(x)+bg(x))=af′(x)+bg′(x)🚫
​

Nice work completing Limits and Derivatives, here's a quick recap of what we covered:

Skills covered

Mixed Practice

Exercises checked off

I'm Plex, here to help you understand this concept!
/
Differentiation
/
Limits and Derivatives
Differentiation rules
Limits and Derivatives
Differentiation

Limits and Derivatives

0 of 0 exercises completed

The basic idea of a limit ​x→alim​f(x)​ from tables and graphs, slope as a limit, rate of change and gradient, derivatives of ​xn, and linearity for sums and scalar multiples.

Want a deeper conceptual understanding? Try our interactive lesson!

Basic concept of a limit
SL 5.1

The limit ​x→alim​f(x)​ is the value ​f(x)​ approaches as ​x​ approaches ​a.

Slope as a Limit
SL 5.1

The IB may test your understanding of the gradient of the curve as the limit of

​
m=x2​−x1​y2​−y1​​
​

as ​(x2​−x1​)​ goes to zero.


Limit from a graph
SL 5.1
​
x→1lim​f(x)=2
​
​
x→∞lim​f(x)=23​
​
​
x→−∞lim​f(x)=23​
​

One way to conceptualize a limit is that in the graph above, we can get as close to an output of ​2​ as we want near ​x=1.


Focus on the right side of the curve as it approaches the hole, we could find an ​x​ so that ​1.9<f(x)<2,  ​1.99<f(x)<2,​ or even ​1.9999<f(x)<2.


The key idea here is that since ​x→1lim​f(x)=2, pick a value as close to ​2​ as you want, and we can find an ​x​-value close enough to ​1​ so that ​f(x)​ is even closer to ​2:

Limit from a table
SL 5.1

Given a table of values:

​
xf(x)​0.91.62​0.991.9121​0.9991.9972201​……​
​


​
x→1lim​f(x)=2
​
Gradient
SL 5.1

For a curve ​y=f(x),  ​f′(x)​ is the function that tells you the slope of ​f(x)​ at a certain ​x​ coordinate.

Graphing a derivative with a GDC
SL 5.1

You can graph ​f′(x)​ using the following steps:

  • Press the Y= key.

  • In one of the available function lines (e.g. Y_1), enter the expression for ​f(x).

  • In another available line (e.g. Y_2), input the derivative function usingMATH then 8:nDeriv( in the following format:

    ​
    dXd​(Y1​(x))∣X=X​
    ​


  • To enter ​Y1​, press VARS then scroll to Y-VARS and select FUNCTION then ​Y1​.

  • Press GRAPH to display both the original graph ​f​ and the derivative ​f′.

  • The graph of ​f′​ may take a little bit longer depending on the original function.

After graphing ​f′, you may use all the other graphing functions on the calculator (intersect, zero, and value).

Rate of Change
SL 5.1

​dxdy​​ is the rate of change of ​y​ with respect to ​x​. That is, ​dxdy​​ tells us how much ​y​ changes in response to a change in ​x.


If ​y=f(x), then ​dxdy​=f′(x).

Derivative of xⁿ where n is an integer
SL 5.3
​
f(x)=xn, n∈Z⇒f′(x)=nxn−1📖
​
Derivatives of sums and scalar multiples
SL 5.3
​
dxd​(af(x))=af′(x)🚫
​
​
dxd​(f(x)+g(x))=f′(x)+g′(x)🚫
​
​
dxd​(af(x)+bg(x))=af′(x)+bg′(x)🚫
​

Nice work completing Limits and Derivatives, here's a quick recap of what we covered:

Skills covered

Mixed Practice

Exercises checked off

I'm Plex, here to help you understand this concept!

Generating starter questions...

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Generating starter questions...

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