Question Details

Let the function f : R R  be defined by

f (x) = sinx/ e πx ( x2023 + 2024x + 2025 x2 x + 3 ) 2 e πx (x2023 + 2024x + 2025)  x2 x + 3

Then the number of solutions of f (x) = 0  in  R  is _____

Show Answer

Correct Answer :

1

Solution :

The correct answer is 1.

Step 1: Simplify and factorize the given function
The given function is defined as:

f (x) = sinx eπx x2023 + 2024x + 2025 x2 x + 3 2 eπx x2023 + 2024x + 2025 x2 x + 3

By taking out the common term, we can re-write f(x) as a product of two expressions:

f (x) = sinx 2 eπx · x2023 + 2024x + 2025 x2 x + 3

Step 2: Analyze the first term
Consider the term:

sinx 2 eπx

1. For all real values of x, the range of the sine function is 1sinx1.
Subtracting 2 gives 3sinx21. Thus, sinx20 for any real x.
2. The exponential expression eπx>0 for all real x.
Therefore, this factor is strictly negative and never equal to zero for any real x.

Step 3: Analyze the rational expression term
Since the first factor is never zero, setting f(x)=0 requires:

x2023 + 2024x + 2025 x2 x + 3 = 0

First, check the denominator x2x+3:
The discriminant is D=(1)24(1)(3)=112=11<0.
Since the leading coefficient is positive (1>0) and the discriminant is negative, x2x+3>0 for all real numbers x. Thus, the denominator is never zero.

Therefore, f(x)=0 reduces strictly to finding the number of real roots of the polynomial numerator:

g(x) = x2023 + 2024x + 2025 = 0

Step 4: Find the number of real roots of g(x)
Let us differentiate g(x) with respect to x:

g(x) = 2023x2022 + 2024

Since x20220 for all real numbers x, we have:

g(x) 2024 > 0

Since g(x)>0 everywhere, g(x) is a strictly increasing function on the set of real numbers.
A continuous, strictly increasing function can cross the x-axis at most once.

Furthermore, since g(x) is a polynomial of odd degree (2023):

limx g(x) =  and  limx g(x) =

By the Intermediate Value Theorem, g(x) must cross the x-axis at least once. Combined with strict monotonicity, it crosses the x-axis exactly once.

Thus, f(x)=0 has exactly 1 solution in R.

Unlock Our Free Library

Access expert-curated educational resources and study materials—completely free.

Discover more resources

You may also like

Mock Tests

View All
  • CTET
  • intermediate
  • No time limit
  • child development and pedagogy, mathematics, social science

  • SSC
  • intermediate
  • 2 hours and 30 mins
  • child development and pedagogy, mathematics, social science

Ask AI Tutor
5 left
Q1 View Question & Options
AI Tutor is solving this question...
Reading question context & options...