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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
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Integration
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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:

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Working on it

Confident

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

IB Math AASL
/
Integration
/
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.

24 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

Definite Integrals, Areas, and Basic Anti-Derivatives

11 skills
Area under a curve
SL 5.5

The area between a curve ​f(x)>0​ and the ​x​-axis is given by

​
A=∫ab​f(x)dx📖
​
Integration as reverse differentiation
SL 5.5

Integration, or anti-differentiation, is essentially the opposite of differentiation. We use the integral symbol​∫​ and write:

​
∫f(x)dx=a function with a derivative off(x)
​

By convention we denote this function ​F:

​
∫f(x)dx=F(x)🚫
​

We can also write

​
∫dxdy​dx=y🚫
​

Notice the ​dx​ under the integral. This tells us which variable we are integrating with respect to - in this case we are reversing ​dxd​.

The Integration Constant
SL 5.5

Since the derivative of a constant is always zero, then if if ​F′(x)=f(x), then ​(F(x)+C)′=f(x).


This means that when we integrate, we can add any constant to our result, since differentiating makes this constant irrelevant:

​
∫f(x)dx=F(x)+C🚫
​
Anti-Derivative of xⁿ, n∈ℤ
SL 5.5
​
∫xndx=n+1xn+1​+C,n∈Z,n=−1📖
​
Integrals of sums and scalar products
SL 5.5

In the same way that constant multiples can pass through the derivative, they can pass through the integral:

​
∫af(x)dx=a∫f(x)dx🚫
​

And in the same way that the derivative of a sum is the sum of the derivatives:

​
∫f(x)+g(x)dx=∫f(x)dx+∫g(x)dx🚫
​
Boundary Conditions
SL 5.5

If we know the value of ​y​ or ​f(x)​ for a given ​x, we can determine ​C​ by plugging in ​x​ and ​y.

Definite Integrals
SL 5.5

A definite integral is evaluated between a lower and upper bound.

​
∫ab​f(x)dx is the integral of f(x)dx from x=a to x=b
​

We can solve a definite integral with

​
∫ab​f(x)dx=[F(x)]ab​=F(b)−F(a)🚫
​


where ​F(x)=∫f(x)dx.

Calculating Definite Integral with GDC
SL 5.5

Graphing calculators can be used to evaluate definite integrals.


For example, on a TI-84, math > 9:fnInt(, which prompts you with ​∫□□​(□)d□. Make sure the variable of your function matches the variable that you take the integral with respect to.

Definite Integral Rules
SL 5.5

Integrals of the same function with adjacent domains can be merged:

​
∫ab​f(x)dx+∫bc​f(x)dx=∫ac​f(x)dx🚫
​

Similarly, the domain of an integral can be split:

​
∫ab​f(x)dx=∫am​f(x)dx+∫mb​f(x)dx🚫
​

for any ​a<m<b.

Area between curve and x-axis
SL 5.11

In general, the area enclosed between a curve and the ​x​-axis is given by

​
A=∫ab​∣f(x)∣dx📖
​

since any region below the ​x​-axis has ​f(x)<0, but area must always be positive.

This can be done with technology, or by splitting the integral into parts - where ​f​ is positive and where ​f​ is negative:

​
A=∫am​f(x)dx+∫mb​−f(x)dx🚫
​
Area between curves
SL 5.11

The area enclosed between two curves is given by

​
A=∫ab​∣f(x)−g(x)∣dx
​

This can be done with technology, or by splitting the integral into multiple regions, each having either ​f(x)>g(x)​ or ​g(x)>f(x).

Anti-Derivative Rules

4 skills
Anti-Derivative of xⁿ, n∈ℚ
SL 5.6
​
∫xndx=n+1xn+1​+C,n=−1📖
​
Anti-Derivative of sin and cos
SL 5.6

The integrals of ​sin​ and ​cos​ are

​
∫sinxdx ∫cosxdx​=−cosx+C📖 =sinx+C📖​
​
Anti-Derivative of e^x
SL 5.6
​
∫exdx=ex+C📖
​
Anti-Derivative of 1/x
SL 5.6
​
∫x1​dx=ln∣x∣+C📖
​

Techniques of Integration

3 skills
Integrating f(ax+b)
SL 5.10

If ​F(x)=∫f(x)dx, then

​
∫f(ax+b)dx=a1​F(ax+b)🚫
​
Integration by substitution
SL 5.10

Integrating a composition of functions ​f(g(x))​ requires us to divide by ​g′(x), so it is easier to find the anti-derivative of anything of the form ​g′(x)f′(g(x))​ by first dividing by ​g′(x).


In symbols, we use the known fact

​
∫kg′(x)f′(g(x))dx=kf(g(x))+C🚫
​

and let ​u=g(x), giving us

​
∫kg′(x)f′(g(x))dx=k∫f′(u)du,🚫
​

an integral we can solve more easily:

​
k∫f′(u)du=kf(u)+C.
​


Then, we substitute ​g(x)​ back in to get our desired result of ​kf(g(x))+C.

Substitution and Integral Bounds
SL 5.10

When we make a substitution in a definite integral in the form

​
∫ab​kg′(x)f′(g(x))dx
​

we need to remember that the bounds are from ​x=a​ to ​x=b:

​
∫ab​kg′(x)f′(g(x))dx  ​=k∫x=ax=b​f′(u)du =[kf(u)]x=ax=b​​
​


We then have two choices:

  1. Plug ​x=a​ and ​x=b​ into ​u​ to find the bounds in terms of ​u.

  2. Plug ​u(x)​ back in and use the bounds ​a→b.

Kinematics

6 skills
Displacement vs Distance
SL 5.9

Displacement ​s​ is the change in position between start and end time, whereas distance ​d​ is the total length of the path taken.


Direction does not matter for distance, which is never negative, but displacement can be negative - usually indicating motion down or to the left.

Displacement, velocity and acceleration
SL 5.9

Acceleration is the rate of change of velocity, which is the rate of change of displacement.


​
v=dtds​🚫\\ 
​
​
a=dtdv​=dt2d2s​📖
​


Hence, the integral of acceleration is velocity, and the integral of velocity is displacement.

Average Velocity and Acceleration
SL 5.9

While we use derivatives to get instantaneous velocity and time, we can also find average velocity and time:

​
average velocity=ΔtΔs​,average acceleration=ΔtΔv​.
​
Change in Displacement from Velocity
SL 5.9

Change in displacement between ​t1​,t2​:

​
∫t1​t2​​v(t)dt📖
​
Speed
SL 5.9

Speed is the magnitude of velocity:

​
speed=∣v∣
​
Distance from Velocity
SL 5.9

The distance can be found from the velocity using the equation

​
∫t1​t2​​∣v(t)∣dt📖
​

Since speed is given by ​∣v(t)∣, we see that distance is the integral of speed.

Skill Checklist

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

24 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

Definite Integrals, Areas, and Basic Anti-Derivatives

11 skills
Area under a curve
SL 5.5

The area between a curve ​f(x)>0​ and the ​x​-axis is given by

​
A=∫ab​f(x)dx📖
​
Integration as reverse differentiation
SL 5.5

Integration, or anti-differentiation, is essentially the opposite of differentiation. We use the integral symbol​∫​ and write:

​
∫f(x)dx=a function with a derivative off(x)
​

By convention we denote this function ​F:

​
∫f(x)dx=F(x)🚫
​

We can also write

​
∫dxdy​dx=y🚫
​

Notice the ​dx​ under the integral. This tells us which variable we are integrating with respect to - in this case we are reversing ​dxd​.

The Integration Constant
SL 5.5

Since the derivative of a constant is always zero, then if if ​F′(x)=f(x), then ​(F(x)+C)′=f(x).


This means that when we integrate, we can add any constant to our result, since differentiating makes this constant irrelevant:

​
∫f(x)dx=F(x)+C🚫
​
Anti-Derivative of xⁿ, n∈ℤ
SL 5.5
​
∫xndx=n+1xn+1​+C,n∈Z,n=−1📖
​
Integrals of sums and scalar products
SL 5.5

In the same way that constant multiples can pass through the derivative, they can pass through the integral:

​
∫af(x)dx=a∫f(x)dx🚫
​

And in the same way that the derivative of a sum is the sum of the derivatives:

​
∫f(x)+g(x)dx=∫f(x)dx+∫g(x)dx🚫
​
Boundary Conditions
SL 5.5

If we know the value of ​y​ or ​f(x)​ for a given ​x, we can determine ​C​ by plugging in ​x​ and ​y.

Definite Integrals
SL 5.5

A definite integral is evaluated between a lower and upper bound.

​
∫ab​f(x)dx is the integral of f(x)dx from x=a to x=b
​

We can solve a definite integral with

​
∫ab​f(x)dx=[F(x)]ab​=F(b)−F(a)🚫
​


where ​F(x)=∫f(x)dx.

Calculating Definite Integral with GDC
SL 5.5

Graphing calculators can be used to evaluate definite integrals.


For example, on a TI-84, math > 9:fnInt(, which prompts you with ​∫□□​(□)d□. Make sure the variable of your function matches the variable that you take the integral with respect to.

Definite Integral Rules
SL 5.5

Integrals of the same function with adjacent domains can be merged:

​
∫ab​f(x)dx+∫bc​f(x)dx=∫ac​f(x)dx🚫
​

Similarly, the domain of an integral can be split:

​
∫ab​f(x)dx=∫am​f(x)dx+∫mb​f(x)dx🚫
​

for any ​a<m<b.

Area between curve and x-axis
SL 5.11

In general, the area enclosed between a curve and the ​x​-axis is given by

​
A=∫ab​∣f(x)∣dx📖
​

since any region below the ​x​-axis has ​f(x)<0, but area must always be positive.

This can be done with technology, or by splitting the integral into parts - where ​f​ is positive and where ​f​ is negative:

​
A=∫am​f(x)dx+∫mb​−f(x)dx🚫
​
Area between curves
SL 5.11

The area enclosed between two curves is given by

​
A=∫ab​∣f(x)−g(x)∣dx
​

This can be done with technology, or by splitting the integral into multiple regions, each having either ​f(x)>g(x)​ or ​g(x)>f(x).

Anti-Derivative Rules

4 skills
Anti-Derivative of xⁿ, n∈ℚ
SL 5.6
​
∫xndx=n+1xn+1​+C,n=−1📖
​
Anti-Derivative of sin and cos
SL 5.6

The integrals of ​sin​ and ​cos​ are

​
∫sinxdx ∫cosxdx​=−cosx+C📖 =sinx+C📖​
​
Anti-Derivative of e^x
SL 5.6
​
∫exdx=ex+C📖
​
Anti-Derivative of 1/x
SL 5.6
​
∫x1​dx=ln∣x∣+C📖
​

Techniques of Integration

3 skills
Integrating f(ax+b)
SL 5.10

If ​F(x)=∫f(x)dx, then

​
∫f(ax+b)dx=a1​F(ax+b)🚫
​
Integration by substitution
SL 5.10

Integrating a composition of functions ​f(g(x))​ requires us to divide by ​g′(x), so it is easier to find the anti-derivative of anything of the form ​g′(x)f′(g(x))​ by first dividing by ​g′(x).


In symbols, we use the known fact

​
∫kg′(x)f′(g(x))dx=kf(g(x))+C🚫
​

and let ​u=g(x), giving us

​
∫kg′(x)f′(g(x))dx=k∫f′(u)du,🚫
​

an integral we can solve more easily:

​
k∫f′(u)du=kf(u)+C.
​


Then, we substitute ​g(x)​ back in to get our desired result of ​kf(g(x))+C.

Substitution and Integral Bounds
SL 5.10

When we make a substitution in a definite integral in the form

​
∫ab​kg′(x)f′(g(x))dx
​

we need to remember that the bounds are from ​x=a​ to ​x=b:

​
∫ab​kg′(x)f′(g(x))dx  ​=k∫x=ax=b​f′(u)du =[kf(u)]x=ax=b​​
​


We then have two choices:

  1. Plug ​x=a​ and ​x=b​ into ​u​ to find the bounds in terms of ​u.

  2. Plug ​u(x)​ back in and use the bounds ​a→b.

Kinematics

6 skills
Displacement vs Distance
SL 5.9

Displacement ​s​ is the change in position between start and end time, whereas distance ​d​ is the total length of the path taken.


Direction does not matter for distance, which is never negative, but displacement can be negative - usually indicating motion down or to the left.

Displacement, velocity and acceleration
SL 5.9

Acceleration is the rate of change of velocity, which is the rate of change of displacement.


​
v=dtds​🚫\\ 
​
​
a=dtdv​=dt2d2s​📖
​


Hence, the integral of acceleration is velocity, and the integral of velocity is displacement.

Average Velocity and Acceleration
SL 5.9

While we use derivatives to get instantaneous velocity and time, we can also find average velocity and time:

​
average velocity=ΔtΔs​,average acceleration=ΔtΔv​.
​
Change in Displacement from Velocity
SL 5.9

Change in displacement between ​t1​,t2​:

​
∫t1​t2​​v(t)dt📖
​
Speed
SL 5.9

Speed is the magnitude of velocity:

​
speed=∣v∣
​
Distance from Velocity
SL 5.9

The distance can be found from the velocity using the equation

​
∫t1​t2​​∣v(t)∣dt📖
​

Since speed is given by ​∣v(t)∣, we see that distance is the integral of speed.