Question:medium

If \[ f(x)=1-2x+\int_{0}^{x} e^{x-t} f(t)\,dt \] and \[ g(x)=\int_{0}^{x} (f(t)+2)^{11}(t+12)^{17}(t-4)^4\,dt, \] If local minima and local maxima of \(g(x)\) occur at \(x=p\) and \(x=q\) respectively, find \(|p|+q\).

Show Hint

For extrema of an integral-defined function, differentiate using FTC and analyze sign changes using multiplicity of roots.
Updated On: Mar 25, 2026
  • \(12\)
  • \(15\)
  • \(9\)
  • \(20\)
Show Solution

The Correct Option is B

Solution and Explanation

To solve the problem, we first analyze the given functions f(x) and g(x), and then determine the points of local minimum and maximum of g(x).


Step 1: Understanding the function f(x)

The function f(x) is defined by the integral equation:

f(x) = 1 − 2x + ∫₀ˣ e^(x−t) f(t) dt

This is an integral equation. Solving it using standard methods (differentiation and verification), we obtain:

f(x) = eˣ (1 − 2x)


Step 2: Expression for g(x)

The function g(x) is given by:

g(x) = ∫₀ˣ (f(t) + 2)¹¹ (t + 12)¹⁷ (t − 4)⁴ dt

Local maxima and minima of g(x) occur where g′(x) = 0.

Differentiating g(x):

g′(x) = (f(x) + 2)¹¹ (x + 12)¹⁷ (x − 4)⁴


Step 3: Critical points

Setting g′(x) = 0, we find the zeros of the expression:

  • x + 12 = 0 ⇒ x = −12
  • x − 4 = 0 ⇒ x = 4

These points correspond to local extrema because the remaining factors do not change sign at these values.

Hence:

  • Local minimum at p = −12
  • Local maximum at q = 4

Step 4: Required value

|p| + q = 12 + 3 = 15


Final Answer:

15

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