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Question

Mathematics Question on Integration by Parts

01(5xe2xtan(π/4))dx=∫_0^1 (5xe^{2x}-tan(π/4)) dx=

A

(54)e2+14 (\dfrac{5}{4}) * e^2 +\dfrac{1}{4}

B

(54)e2+94 (\dfrac{5}{4}) * e^2 +\dfrac{9}{4}

C

(34)e2+14 (\dfrac{3}{4}) * e^2 +\dfrac{1}{4}

D

(14)e2+54 (\dfrac{1}{4}) * e^2 +\dfrac{5}{4}

E

(54)e2 (\dfrac{5}{4}) * e^2

Answer

(54)e2 (\dfrac{5}{4}) * e^2

Explanation

Solution

The correct option is (E): (54)e2(\dfrac{5}{4}) * e^2
Step 1:
Find the antiderivative of each term:
(5xe2xtan(π4))dx∫(5xe^{2x}- tan(\dfrac{π}{4})) dx
The antiderivative of 5xe2x5xe^{2x} with respect to xx can be found using integration by parts.
Let's take t=5xt = 5x and dt=e2xdxdt = e^{2x} dx.
Then, dt=5dxdt = 5 dx and u=12e2xu = \dfrac{1}{2}e^{2x}.
Using the integration by parts formula: ∫u dv = uv - ∫v du
We get: (5xe2x)dx=(12)5xe2x(12)e(2x)5dx∫(5xe^{2x}) dx = (\frac{1}{2}) * 5x * e^{2x} - ∫(\frac{1}{2})e^{(2x)} * 5 dx
=52xe2x52e2xdx= \dfrac{5}{2}x * e^{2x}- \dfrac{5}{2}∫e^{2x} dx
=52xe2x5212e2x+C1= \dfrac{5}{2}x * e^{2x} - \dfrac{5}{2} * \dfrac{1}{2}e^{2x} + C_1
= 52xe2x54e2x+C1\dfrac{5}{2}x * e^{2x} - \dfrac{5}{4}e^{2x} + C_1
The antiderivative of tan(π4)tan\,(\frac{π}{4}) with respect to xx is simply -x since tan(π4)tan\,(\frac{π}{4}) is a constant.
_Step 2: _
Apply the limits:
01(5xe2xtan(π/4))dx∫_0^1(5xe^{2x} - tan(π/4)) dx
=[521e2154e21+C1][0C1]=[\dfrac{5}{2}1e^{2*1} - \dfrac{5}{4}e^{2*1} + C_1] - [0 - C_1]
=[52e254e2]+C1(C1)= [\dfrac{5}{2}*e^2 - \dfrac{5}{4}*e^2] + C1 - (- C1)
=(5254)e2=54e2= (\dfrac{5}{2} - \dfrac{5}{4}) * e^{2} = \dfrac{5}{4} * e^2
=(54)e2= (\dfrac{5}{4}) * e^2 (_Ans)