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Question

Mathematics Question on Definite Integral

Let [t][t] denote the greatest integer less than or equal to t Then the value of the integral 3101([sin(πx)]+e[cos(2πx)])dx\int\limits_{-3}^{101}\left([\sin (\pi x)]+e^{[\cos (2 \pi x)]}\right) d x is equal to

A

52(1e)e\frac{52(1- e )}{ e }

B

52e\frac{52}{ e }

C

52(2+e)e\frac{52(2+ e )}{ e }

D

104e\frac{104}{ e }

Answer

52e\frac{52}{ e }

Explanation

Solution

−3∫101​([sinπx]+e[cos2πx])dx
520∫2​([sinπx]+e[cos2πx])dt
π52​0∫2π​([sint]+e[cos2t])dt
π52​0∫2π​([sint]dt+0∫2π​e[cos2t]dt)
I1​=0∫2π​[sint]dt
Using King
I1​=0∫2π​[−sint]dt
2I1​=0∫2π​(−1)dt=−2π
I1​=−π
I2​=20∫π​e[cos2t]dt
=2.20∫π/2​e[cos2t]dt
=4(0∫π/4​e0⋅dt+π/4∫π/2​e−1dt)
4(4π​+e−1(4π​))=π(1+e−1)
I=π52​(−π+π+πe−1)=e52​