I need help evaluating the above integral. Any help would be useful thanks.
indefinite integral (e^(2x))(sin(5x))dx
let u=e^(2x)
du=2e^(2x)
let dv=sin(5x) dx
v=-1/5cos(5x)
∫(e^(2x))(sin(5x))dx=-1/5cos(5x)e^(2x)-∫-2/5cos(5x)e^(2x) dx
∫-2/5cos(5x)e^(2x) dx=-2/5∫cos(5x)e^(2x) dx
u=e^(2x)
let dw=cos(5x) dx
w=1/5sin(5x)
∫cos(5x)e^(2x)=1/5e^(2x)sin(5x)-∫2/5sin(5x)e^(2x)
∫(e^(2x))(sin(5x))dx=-1/5cos(5x)e^(2x)+2/5∫cos(5x)e^(2x) dx
∫(e^(2x))(sin(5x))dx=-1/5cos(5x)e^(2x)+(2/5)(1/5e^(2x)sin(5x)-2/5∫sin(5x)e^(2x) dx)
let I=∫e^(2x)sin(5x) dx
I=-1/5cos(5x)e^(2x) + (2/5)(1/5e^(2x)sin(5x)-2/5I
7/5I=-1/5cos(5x)e^(2x) + (2/5)(1/5e^(2x)sin(5x)
I=-1/7cos(5x)e^(2x) + (35/2)e^(2x)sin(5x)+C
Integration by parts is explained with a link in the source. It is much easier to do in terms of functions and derivatives rather than differencials.
Integrate the original integrand by parts:
∫ e²˟sin(5x) dx
Let f'(x) = e²˟
f(x) = e²˟ / 2
Let g(x) = sin(5x)
g'(x) = 5cos(5x)
∫ f'(x)g(x) dx = f(x)g(x) - ∫ f(x)g'(x) dx
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - ∫ 5e²˟cos(5x) / 2 dx
Integrate the new integrand by parts:
∫ 5e²˟cos(5x) / 2 dx
Let f'(x) = e²˟ / 2
f(x) = e²˟ / 4
Let g(x) = 5cos(5x)
g'(x) = -25sin(5x)
∫ 5e²˟cos(5x) / 2 dx = 5e²˟cos(5x) / 4 + ∫ 25e²˟sin(5x) / 4 dx
Put it all together and collect like terms to solve for the integral:
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - [5e²˟cos(5x) / 4 + ∫ 25e²˟sin(5x) / 4 dx]
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - 5e²˟cos(5x) / 4 - ∫ 25e²˟sin(5x) / 4 dx
29 ∫ e²˟sin(5x) dx / 4 = e²˟sin(5x) / 2 - 5e²˟cos(5x) / 4
∫ e²˟sin(5x) dx = [2e²˟sin(5x) - 5e²˟cos(5x)] / 29 + C
integrate by parts
i.e. =integral(e^(2x) d/(dx) (-1/5 cos(5x)) dx=-1/5cos(5x) e^(2x) + 2/5 integral(e^(2x)cos(5x))
integral(e^(2x)cos(5x))=integral(e^(2x) d/(dx) (1/5)sin(5x))=1/5sin(5x) e^(2x) - 2/5 integral(e^(2x)sin(5x))
therefore integral (e^(2x))(sin(5x))dx=-1/5cos(5x) e^(2x) +2/5 (1/5sin(5x) e^(2x) - 2/5 integral(e^(2x)sin(5x)) )= 2/25 sin(5x)e^(2x) -1/5cos(5x) e^(2x) - 4/25 integral(e^(2x)sin(5x))
therefore 29/25 integral(e^(2x)sin(5x))=2/25 sin(5x)e^(2x) -1/5cos(5x) e^(2x)
therefore integral(e^(2x)sin(5x))=25/29 (2/25 sin(5x)e^(2x) -1/5cos(5x) e^(2x)) = 2/29 sin(5x)e^(2x) - 5/29 cos(5x) e^(2x)
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Answers & Comments
Verified answer
let u=e^(2x)
du=2e^(2x)
let dv=sin(5x) dx
v=-1/5cos(5x)
∫(e^(2x))(sin(5x))dx=-1/5cos(5x)e^(2x)-∫-2/5cos(5x)e^(2x) dx
∫-2/5cos(5x)e^(2x) dx=-2/5∫cos(5x)e^(2x) dx
u=e^(2x)
du=2e^(2x)
let dw=cos(5x) dx
w=1/5sin(5x)
∫cos(5x)e^(2x)=1/5e^(2x)sin(5x)-∫2/5sin(5x)e^(2x)
∫(e^(2x))(sin(5x))dx=-1/5cos(5x)e^(2x)+2/5∫cos(5x)e^(2x) dx
∫(e^(2x))(sin(5x))dx=-1/5cos(5x)e^(2x)+(2/5)(1/5e^(2x)sin(5x)-2/5∫sin(5x)e^(2x) dx)
let I=∫e^(2x)sin(5x) dx
I=-1/5cos(5x)e^(2x) + (2/5)(1/5e^(2x)sin(5x)-2/5I
7/5I=-1/5cos(5x)e^(2x) + (2/5)(1/5e^(2x)sin(5x)
I=-1/7cos(5x)e^(2x) + (35/2)e^(2x)sin(5x)+C
Integration by parts is explained with a link in the source. It is much easier to do in terms of functions and derivatives rather than differencials.
Integrate the original integrand by parts:
∫ e²˟sin(5x) dx
Let f'(x) = e²˟
f(x) = e²˟ / 2
Let g(x) = sin(5x)
g'(x) = 5cos(5x)
∫ f'(x)g(x) dx = f(x)g(x) - ∫ f(x)g'(x) dx
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - ∫ 5e²˟cos(5x) / 2 dx
Integrate the new integrand by parts:
∫ 5e²˟cos(5x) / 2 dx
Let f'(x) = e²˟ / 2
f(x) = e²˟ / 4
Let g(x) = 5cos(5x)
g'(x) = -25sin(5x)
∫ f'(x)g(x) dx = f(x)g(x) - ∫ f(x)g'(x) dx
∫ 5e²˟cos(5x) / 2 dx = 5e²˟cos(5x) / 4 + ∫ 25e²˟sin(5x) / 4 dx
Put it all together and collect like terms to solve for the integral:
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - ∫ 5e²˟cos(5x) / 2 dx
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - [5e²˟cos(5x) / 4 + ∫ 25e²˟sin(5x) / 4 dx]
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - 5e²˟cos(5x) / 4 - ∫ 25e²˟sin(5x) / 4 dx
∫ e²˟sin(5x) dx = e²˟sin(5x) / 2 - 5e²˟cos(5x) / 4 - ∫ 25e²˟sin(5x) / 4 dx
29 ∫ e²˟sin(5x) dx / 4 = e²˟sin(5x) / 2 - 5e²˟cos(5x) / 4
∫ e²˟sin(5x) dx = [2e²˟sin(5x) - 5e²˟cos(5x)] / 29 + C
integrate by parts
i.e. =integral(e^(2x) d/(dx) (-1/5 cos(5x)) dx=-1/5cos(5x) e^(2x) + 2/5 integral(e^(2x)cos(5x))
integral(e^(2x)cos(5x))=integral(e^(2x) d/(dx) (1/5)sin(5x))=1/5sin(5x) e^(2x) - 2/5 integral(e^(2x)sin(5x))
therefore integral (e^(2x))(sin(5x))dx=-1/5cos(5x) e^(2x) +2/5 (1/5sin(5x) e^(2x) - 2/5 integral(e^(2x)sin(5x)) )= 2/25 sin(5x)e^(2x) -1/5cos(5x) e^(2x) - 4/25 integral(e^(2x)sin(5x))
therefore 29/25 integral(e^(2x)sin(5x))=2/25 sin(5x)e^(2x) -1/5cos(5x) e^(2x)
therefore integral(e^(2x)sin(5x))=25/29 (2/25 sin(5x)e^(2x) -1/5cos(5x) e^(2x)) = 2/29 sin(5x)e^(2x) - 5/29 cos(5x) e^(2x)