Let the function be defined by
Then the number of solutions of f(x) = 0 in R is ______.
Correct Answer :
Solution :
To find the number of solutions of the equation in the set of real numbers , let us first write down the expression for the function:
We can factor out the common terms from both parts of the sum:
Now, let us analyze each factor to find the roots of the equation :
1. The denominator:
The term is strictly positive for all real numbers .
The quadratic term has a discriminant of . Since the discriminant is negative and the leading coefficient is positive, for all .
Therefore, the denominator is always positive and never zero.
2. The trigonometric factor:
Since the range of the sine function is , we have:
Thus, the term is strictly positive and can never be zero.
3. The numerator polynomial:
Since the other components of are non-zero, the equation simplifies to finding the real roots of the polynomial:
Let us find the derivative of with respect to :
Since the exponent is even, for all real numbers .
Therefore, for all .
Since the derivative is strictly positive, the function is strictly increasing on .
Because is a continuous polynomial of odd degree (2023), it must have at least one real root. Since it is also strictly increasing, it can cross the x-axis exactly once.
Therefore, the equation (and consequently ) has exactly 1 real solution.
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