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Perplex
Perplex
Dashboard
Topics
Exponents & LogarithmsApproximations & ErrorSequences & SeriesCounting & BinomialsProof and Reasoning
Cartesian plane & linesQuadraticsFunction TheoryTransformations & asymptotes
2D & 3D GeometryTrig equations & identities
ProbabilityDescriptive StatisticsBivariate StatisticsDistributions & Random Variables
DifferentiationIntegration
Review VideosFormula BookletMy Progress
BlogLanding Page
Sign UpLogin
Perplex
IB Math AASL
/
Differentiation
/
Skills
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Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

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📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

IB Math AASL
/
Differentiation
/
Skills
Edit

Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

25 Skills Available

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Limits and Derivatives

9 skills
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​
​
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 gradient or slope.

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)🚫
​

Differentiation rules

8 skills
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)🚫
​
Derivative of xⁿ where n is rational
SL 5.6
​
f(x)=xn, n∈Q⇒f′(x)=nxn−1📖
​
Chain rule
SL 5.6
​
(g(f(x)))′=g′(f(x))⋅f′(x)🚫
​
​
y=g(u) where u=f(x)
​
​
dxdy​=dudg​⋅dxdu​📖
​
Derivative of e^x
SL 5.6
​
f(x)=ex⇒f′(x)=ex📖
​
Derivative of ln
SL 5.6
​
f(x)=lnx⇒f′(x)=x1​📖
​
Product and Quotient rule
SL 5.6

The product and quotient rules are given by

​
(uv)′=u′v+v′u📖
​
​
(vu​)′=v2u′v−v′u​📖
​
Derivatives of sin and cos
SL 5.6
​
f(x)=sinx⇒f′(x)=cosx📖
​
​
g(x)=cosx⇒g′(x)=−sinx📖
​

Tangents and normals

2 skills
Tangent to f(x)
SL 5.4

​L:mx+c​ is tangent to ​f(x)​ at ​x=a​ means

​
same ysame y′​{f(a)=ma+cf′(a)=m​🚫
​

Using point slope form the equation of the tangent is:

​
y−f(a) ⇒y​=m⋅(x−a)🚫 =mx−ma+f(a)🚫​
​


Normal to f(x)
SL 5.4

The normal to ​f(x)​ at ​x=a​ is the line that passes through ​(a,f(a))​ and is perpendicular to the tangent:

​
mn​⋅mt​=−1⇔mn​  ​=−mt​1​🚫 =−f′(a)1​🚫​
​

Using point slope form the equation of the tangent is:

​
y−f(a) ⇒y​=mn​⋅(x−a)🚫 =mn​x−mn​a+f(a)🚫​
​

Applications of the First Derivative

3 skills
Stationary points & Increasing/Decreasing Regions
SL 5.2
​
f′(x)⎩⎪⎨⎪⎧​<0⇔f decreasing=0⇔f stationary>0⇔f increasing​🚫
​
Maxima & Minima
SL 5.7

Stationary points are often local extrema.


If ​f′(a)=0,  ​f​ is decreasing to the left of ​a​ (​f′(x)<0​), and ​f​ is increasing to the right of ​a​ (​f′(x)>0​), then ​(a,f(a))​ is a local minimum.


If ​f′(a)=0,  ​f​ is increasing to the left of ​a​ (​f′(x)<0​), and ​f​ is decreasing to the right of ​a​ (​f′(x)>0​), then ​(a,f(a))​ is a local maximum.

Optimisation
SL 5.8

Optimisation problems require you to find a minimum or maximum value by producing a function ​f(x), taking its derivative, solving ​f′(x)=0, and confirming which stationary point(s) are minima or maxima.

Second Derivatives and Applications

5 skills
Second Derivative
SL 5.7

The derivative of the derivative of a function is its second derivative:

​
f′′(x)=(f′(x))′🚫
​
​
dx2d2y​=dxd​(dxdy​)=y′′🚫
​
Concavity
SL 5.7

We determine concavity by the sign of ​f′′:

​
f′′{>0⇔f concave up<0⇔f concave down​🚫
​
Classifying stationary points using the second derivative
SL 5.7

At a stationary point (​f′(a)=0​),

  • If ​f′′(a)>0, then ​f​ has a local minimum at ​x=a.

  • If ​f′′(a)<0, then ​f​ has a local maximum at ​x=a.

Using the second derivative to classify a stationary point is often called the second derivative test.

Inflexion Points
SL 5.7

Inflexion points occur when ​f′′(x)=0​ and ​f′′(x)​ changes sign. 🚫

Graphs of f, f' and f''
SL 5.7
  • When ​f′​ crosses the ​x​-axis ​f​ has a maximum (​f′′<0​) or minimum (​f′′>0​)

  • When ​f′′​ crosses the ​x​-axis, ​f​ has an inflexion point.

Skill Checklist

Track your progress across all skills in your objective. Mark your confidence level and identify areas to focus on.

25 Skills Available

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Track your progress:

Don't know

Working on it

Confident

📖 = included in formula booklet • 🚫 = not in formula booklet

Limits and Derivatives

9 skills
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​
​
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 gradient or slope.

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)🚫
​

Differentiation rules

8 skills
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)🚫
​
Derivative of xⁿ where n is rational
SL 5.6
​
f(x)=xn, n∈Q⇒f′(x)=nxn−1📖
​
Chain rule
SL 5.6
​
(g(f(x)))′=g′(f(x))⋅f′(x)🚫
​
​
y=g(u) where u=f(x)
​
​
dxdy​=dudg​⋅dxdu​📖
​
Derivative of e^x
SL 5.6
​
f(x)=ex⇒f′(x)=ex📖
​
Derivative of ln
SL 5.6
​
f(x)=lnx⇒f′(x)=x1​📖
​
Product and Quotient rule
SL 5.6

The product and quotient rules are given by

​
(uv)′=u′v+v′u📖
​
​
(vu​)′=v2u′v−v′u​📖
​
Derivatives of sin and cos
SL 5.6
​
f(x)=sinx⇒f′(x)=cosx📖
​
​
g(x)=cosx⇒g′(x)=−sinx📖
​

Tangents and normals

2 skills
Tangent to f(x)
SL 5.4

​L:mx+c​ is tangent to ​f(x)​ at ​x=a​ means

​
same ysame y′​{f(a)=ma+cf′(a)=m​🚫
​

Using point slope form the equation of the tangent is:

​
y−f(a) ⇒y​=m⋅(x−a)🚫 =mx−ma+f(a)🚫​
​


Normal to f(x)
SL 5.4

The normal to ​f(x)​ at ​x=a​ is the line that passes through ​(a,f(a))​ and is perpendicular to the tangent:

​
mn​⋅mt​=−1⇔mn​  ​=−mt​1​🚫 =−f′(a)1​🚫​
​

Using point slope form the equation of the tangent is:

​
y−f(a) ⇒y​=mn​⋅(x−a)🚫 =mn​x−mn​a+f(a)🚫​
​

Applications of the First Derivative

3 skills
Stationary points & Increasing/Decreasing Regions
SL 5.2
​
f′(x)⎩⎪⎨⎪⎧​<0⇔f decreasing=0⇔f stationary>0⇔f increasing​🚫
​
Maxima & Minima
SL 5.7

Stationary points are often local extrema.


If ​f′(a)=0,  ​f​ is decreasing to the left of ​a​ (​f′(x)<0​), and ​f​ is increasing to the right of ​a​ (​f′(x)>0​), then ​(a,f(a))​ is a local minimum.


If ​f′(a)=0,  ​f​ is increasing to the left of ​a​ (​f′(x)<0​), and ​f​ is decreasing to the right of ​a​ (​f′(x)>0​), then ​(a,f(a))​ is a local maximum.

Optimisation
SL 5.8

Optimisation problems require you to find a minimum or maximum value by producing a function ​f(x), taking its derivative, solving ​f′(x)=0, and confirming which stationary point(s) are minima or maxima.

Second Derivatives and Applications

5 skills
Second Derivative
SL 5.7

The derivative of the derivative of a function is its second derivative:

​
f′′(x)=(f′(x))′🚫
​
​
dx2d2y​=dxd​(dxdy​)=y′′🚫
​
Concavity
SL 5.7

We determine concavity by the sign of ​f′′:

​
f′′{>0⇔f concave up<0⇔f concave down​🚫
​
Classifying stationary points using the second derivative
SL 5.7

At a stationary point (​f′(a)=0​),

  • If ​f′′(a)>0, then ​f​ has a local minimum at ​x=a.

  • If ​f′′(a)<0, then ​f​ has a local maximum at ​x=a.

Using the second derivative to classify a stationary point is often called the second derivative test.

Inflexion Points
SL 5.7

Inflexion points occur when ​f′′(x)=0​ and ​f′′(x)​ changes sign. 🚫

Graphs of f, f' and f''
SL 5.7
  • When ​f′​ crosses the ​x​-axis ​f​ has a maximum (​f′′<0​) or minimum (​f′′>0​)

  • When ​f′′​ crosses the ​x​-axis, ​f​ has an inflexion point.