Integral of x^2sinx^3dx dx
The solution
Detail solution
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=x2 and let dv(x)=sin3(x).
Then du(x)=2x.
To find v(x):
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Rewrite the integrand:
sin3(x)=(1−cos2(x))sin(x)
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There are multiple ways to do this integral.
Method #1
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Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(u2−1)du
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Integrate term-by-term:
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The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
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The integral of a constant is the constant times the variable of integration:
∫(−1)du=−u
The result is: 3u3−u
Now substitute u back in:
3cos3(x)−cos(x)
Method #2
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Rewrite the integrand:
(1−cos2(x))sin(x)=−sin(x)cos2(x)+sin(x)
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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:
∫(−sin(x)cos2(x))dx=−∫sin(x)cos2(x)dx
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Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u2du
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The integral of a constant times a function is the constant times the integral of the function:
∫(−u2)du=−∫u2du
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The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: −3u3
Now substitute u back in:
−3cos3(x)
So, the result is: 3cos3(x)
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The integral of sine is negative cosine:
∫sin(x)dx=−cos(x)
The result is: 3cos3(x)−cos(x)
Method #3
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Rewrite the integrand:
(1−cos2(x))sin(x)=−sin(x)cos2(x)+sin(x)
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Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−sin(x)cos2(x))dx=−∫sin(x)cos2(x)dx
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u2du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u2)du=−∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: −3u3
Now substitute u back in:
−3cos3(x)
So, the result is: 3cos3(x)
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The integral of sine is negative cosine:
∫sin(x)dx=−cos(x)
The result is: 3cos3(x)−cos(x)
Now evaluate the sub-integral.
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Use integration by parts:
∫udv=uv−∫vdu
Let u(x)=32x and let dv(x)=cos3(x)−3cos(x).
Then du(x)=32.
To find v(x):
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Integrate term-by-term:
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Rewrite the integrand:
cos3(x)=(1−sin2(x))cos(x)
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Let u=sin(x).
Then let du=cos(x)dx and substitute du:
∫(1−u2)du
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Integrate term-by-term:
-
The integral of a constant is the constant times the variable of integration:
∫1du=u
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The integral of a constant times a function is the constant times the integral of the function:
∫(−u2)du=−∫u2du
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
So, the result is: −3u3
The result is: −3u3+u
Now substitute u back in:
−3sin3(x)+sin(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−3cos(x))dx=−3∫cos(x)dx
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The integral of cosine is sine:
∫cos(x)dx=sin(x)
So, the result is: −3sin(x)
The result is: −3sin3(x)−2sin(x)
Now evaluate the sub-integral.
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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:
∫(−92sin3(x))dx=−92∫sin3(x)dx
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Rewrite the integrand:
sin3(x)=(1−cos2(x))sin(x)
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫(u2−1)du
-
Integrate term-by-term:
-
The integral of un is n+1un+1 when n=−1:
∫u2du=3u3
-
The integral of a constant is the constant times the variable of integration:
∫(−1)du=−u
The result is: 3u3−u
Now substitute u back in:
3cos3(x)−cos(x)
So, the result is: −272cos3(x)+92cos(x)
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The integral of a constant times a function is the constant times the integral of the function:
∫(−34sin(x))dx=−34∫sin(x)dx
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The integral of sine is negative cosine:
∫sin(x)dx=−cos(x)
So, the result is: 34cos(x)
The result is: −272cos3(x)+914cos(x)
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Now simplify:
3x2(cos2(x)−3)cos(x)+92x(sin2(x)+6)sin(x)−272cos3(x)+914cos(x)
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Add the constant of integration:
3x2(cos2(x)−3)cos(x)+92x(sin2(x)+6)sin(x)−272cos3(x)+914cos(x)+constant
The answer is:
3x2(cos2(x)−3)cos(x)+92x(sin2(x)+6)sin(x)−272cos3(x)+914cos(x)+constant
The answer (Indefinite)
[src]
/ 3 \
/ | sin (x)|
| 3 / 3 \ 2*x*|-2*sin(x) - -------|
| 2 3 2*cos (x) 14*cos(x) 2 | cos (x)| \ 3 /
| x *sin (x)*1 dx = C - --------- + --------- + x *|-cos(x) + -------| - -------------------------
| 27 9 \ 3 / 3
/
−1086xsin(3x)+(2−9x2)cos(3x)−162xsinx+(81x2−162)cosx
The graph
3 3 2 2
40 14*sin (1) 22*cos (1) 4*cos (1)*sin(1) 5*sin (1)*cos(1)
- -- + ---------- + ---------- + ---------------- + ----------------
27 9 27 3 9
−1086sin3−7cos3−162sin1−81cos1−2740
=
3 3 2 2
40 14*sin (1) 22*cos (1) 4*cos (1)*sin(1) 5*sin (1)*cos(1)
- -- + ---------- + ---------- + ---------------- + ----------------
27 9 27 3 9
−2740+2722cos3(1)+95sin2(1)cos(1)+34sin(1)cos2(1)+914sin3(1)
Use the examples entering the upper and lower limits of integration.