Integral of tg^3xdx/cos^2x dx
The solution
Detail solution
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Rewrite the integrand:
tan3(x)sec2(x)=(sec2(x)−1)tan(x)sec2(x)
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There are multiple ways to do this integral.
Method #1
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Let u=sec2(x).
Then let du=2tan(x)sec2(x)dx and substitute du:
∫(2u−21)du
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Integrate term-by-term:
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The integral of a constant times a function is the constant times the integral of the function:
∫2udu=2∫udu
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The integral of un is n+1un+1 when n=−1:
∫udu=2u2
So, the result is: 4u2
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The integral of a constant is the constant times the variable of integration:
∫(−21)du=−2u
The result is: 4u2−2u
Now substitute u back in:
4sec4(x)−2sec2(x)
Method #2
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Rewrite the integrand:
(sec2(x)−1)tan(x)sec2(x)=tan(x)sec4(x)−tan(x)sec2(x)
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Integrate term-by-term:
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Let u=sec4(x).
Then let du=4tan(x)sec4(x)dx and substitute 4du:
∫161du
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The integral of a constant times a function is the constant times the integral of the function:
∫41du=4∫1du
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The integral of a constant is the constant times the variable of integration:
∫1du=u
So, the result is: 4u
Now substitute u back in:
4sec4(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−tan(x)sec2(x))dx=−∫tan(x)sec2(x)dx
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Let u=sec2(x).
Then let du=2tan(x)sec2(x)dx and substitute 2du:
∫41du
-
The integral of a constant times a function is the constant times the integral of the function:
∫21du=2∫1du
-
The integral of a constant is the constant times the variable of integration:
∫1du=u
So, the result is: 2u
Now substitute u back in:
2sec2(x)
So, the result is: −2sec2(x)
The result is: 4sec4(x)−2sec2(x)
Method #3
-
Rewrite the integrand:
(sec2(x)−1)tan(x)sec2(x)=tan(x)sec4(x)−tan(x)sec2(x)
-
Integrate term-by-term:
-
Let u=sec4(x).
Then let du=4tan(x)sec4(x)dx and substitute 4du:
∫161du
-
The integral of a constant times a function is the constant times the integral of the function:
∫41du=4∫1du
-
The integral of a constant is the constant times the variable of integration:
∫1du=u
So, the result is: 4u
Now substitute u back in:
4sec4(x)
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−tan(x)sec2(x))dx=−∫tan(x)sec2(x)dx
-
Let u=sec2(x).
Then let du=2tan(x)sec2(x)dx and substitute 2du:
∫41du
-
The integral of a constant times a function is the constant times the integral of the function:
∫21du=2∫1du
-
The integral of a constant is the constant times the variable of integration:
∫1du=u
So, the result is: 2u
Now substitute u back in:
2sec2(x)
So, the result is: −2sec2(x)
The result is: 4sec4(x)−2sec2(x)
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Now simplify:
4(sec2(x)−2)sec2(x)
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Add the constant of integration:
4(sec2(x)−2)sec2(x)+constant
The answer is:
4(sec2(x)−2)sec2(x)+constant
The answer (Indefinite)
[src]
/
| 2 4
| 3 1 sec (x) sec (x)
| tan (x)*1*------- dx = C - ------- + -------
| 2 2 4
| cos (x)
|
/
4sin4x−8sin2x+42sin2x−1
The graph
2
1 1 - 2*cos (1)
- + -------------
4 4
4*cos (1)
−4sin41−8sin21+41+2sin41−4sin21+2sin21+41
=
2
1 1 - 2*cos (1)
- + -------------
4 4
4*cos (1)
41+4cos4(1)1−2cos2(1)
Use the examples entering the upper and lower limits of integration.