Cubic Function Solution Found

Anonymous

There is a cubic function with a leading coefficient of positive (f(x) ).

For function (g(x) = e^{(\sin \pi x)} - 1 ), a composite function (h(x) = g(f(x)) ) defined in every set of real numbers.

Both functions (f(x) ) and the composite function (h(x) = g(f(x)) ) are The conditions are satisfied. (a), (b): (a) The function ( h(x) ) has a local maximum value of 0 at ( x = 0 ). (b) In the open interval (0, 3), the number of different real roots of the equation h(z)=1 is 7.

When if (f(3) = 1/2 ) and (f'(3) = 0 ), then (f(2) = q/p ), find the value of (p + q , where p and q are coprime natural numbers.

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To solve this problem, let's analyze the given conditions and information step-by-step:

Analyzing ( h(x) = g(f(x)) )

Given: ( g(x) = e^{\sin(\pi x)} - 1 ) and ( h(x) = g(f(x)) )

Condition (a): Local Maximum at ( x = 0 )

  1. ( h(x) ) has a local maximum at ( x = 0 ).
  2. ( h(0) = 0 ).
  3. From the definition of ( h(x) ), we have ( g(f(0)) = 0 ).

Condition (b): Roots of ( h(z) = 1 ) in (0, 3)

There are 7 different real roots of ( h(z) = 1 ) in the interval (0, 3).

Additional Information

  1. ( f(3) = \frac{1}{2} ).
  2. ( f'(3) = 0 ) (indicating a local extremum or point of inflection at ( x = 3 )).

Goal

Find ( f(2) = \frac{q}{p} ) and calculate ( p + q ) where ( p ) and ( q ) are coprime natural numbers.

Approach

  1. Derive the general form of ( f(x) ) considering it's a cubic function with a positive leading coefficient.
  2. Use the given conditions to find specific coefficients.
  3. Evaluate ( f(2) ) and simplify to the form ( \frac{q}{p} ).
  4. Calculate ( p + q ).

Let's start by setting up the cubic function ( f(x) ) and then proceed to apply the conditions.

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The cubic function ( f(x) ) is now updated to ( f(x) = ax^3 + bx^2 + cx ) after applying condition (a), which gives ( d = 0 ) (since ( h(0) = 0 )).

Next, let's use the additional information ( f(3) = \frac{1}{2} ) and ( f'(3) = 0 ) to solve for the coefficients ( a ), ( b ), and ( c ). We'll then calculate ( f(2) ) and determine ( p + q ).

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It seems we encountered an issue while solving for the coefficients ( a ), ( b ), and ( c ). This might be due to the system of equations not having a unique solution with the given constraints.

To address this, let's try a different approach. We know that ( f(x) ) is a cubic function with a positive leading coefficient and satisfies ( f(3) = \frac{1}{2} ) and ( f'(3) = 0 ). We can use these conditions directly to form and solve the system of equations.

Let's proceed with this method:

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The simplified value of ( f(2) ) is approximately ( 2.44444444444445 ). This number is very close to ( \frac{22}{9} ), which is a rational number with coprime numerator and denominator. Let's verify if ( f(2) ) is exactly ( \frac{22}{9} ) and then calculate ( p + q ) where ( p ) and ( q ) are the numerator and denominator of the fraction, respectively.

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The value of ( f(2) ) is indeed exactly ( \frac{22}{9} ). Therefore, with ( p = 22 ) and ( q = 9 ) as the numerator and denominator of the fraction, the sum ( p + q ) is ( 31 ).