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Question: Answered & Verified by Expert
Let the function F be defined as F x = 1 x   e t t dt x > 0 , then the value of the integral 1 x e t t + a dt , where a>0, is
MathematicsDefinite IntegrationJEE Main
Options:
  • A e a F x - F 1 + a
  • B e - a F x + a - F a
  • C e a F x + a - F 1 + a
  • D e - a F x + a - F 1 + a
Solution:
2001 Upvotes Verified Answer
The correct answer is: e - a F x + a - F 1 + a
F x = 1 x e t t dt

I = 1 x e t t + a dt

Let,  t + a = y   ⇒   dt = dy

Also,  t = 1  ⇒  y = 1 + a  and t = x  ⇒  y = x + a

∴    I = 1 + a x + a e y - a y dy

          = e - a 1 + a x + a e y y dy

          = e - a 1 + a x + a e t t dt

          = e - a F x + a - F 1 + a

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