Engineering
Mathematics
Leibnitz Rule Derivative of Anti Derivatives
Question

Let f(x) = Limα→0 1α4∫0α(ex+t−ex) sint · ln (1+t) · (2017t3+4)(2018t3+1) dt and g(x) be a real valued function and satisfying g(x) = x2 + ∫−11(x+y) g(y) dy .  Then

[Note: [z] denotes greatest integer function less than or equal to z.]

number of solutions of f(x) = g(x + 1) + 73  is  2.

Number of solutions of f(x) = g(x + 1) + 73  is  1.

[f(1)] = 2

[g(1)] = – 3

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Solution

f(x) =Limα→0 ex (eα−1) · sinα · ℓn (1+α) (2017α3+4)4α3 (2018α3+1)=ex

and f(x) = x2+x∫−11g(y) dy+∫−11yg(y) dy

Let A=∫−11g(y) dyand B=∫−11yg(y) dy

∴ g(x) = x2 + Ax + B

∴ A=∫−11(y2+Ay+B) dy=2(y33+By)01=23+2B

⇒A−2B=23

and B =∫−11(y3+Ay2+By) dy

=2(Ay33)01=2A3

∴A−4A3=23⇒A= −2 and B=−43

∴g(x) = x2 – 2x –43 = (x – 1)2 – 73.

∴f(x) = g(x + 1) +73

⇒ ex = x2 ⇒ x2e–x = 1

∴ Clearly number of solutions = 1.