Find the Value of $f(102)$ for $f(x)$ of Degree 100

In summary, the value of $f(102)$ for $f(x)$ of Degree 100 can be found by plugging in 102 for the variable x in the given equation and solving for f(x). This value can be negative, a fraction, and is not the same as finding the x-intercept. It is significant for understanding the behavior of the function at a specific input value and can be used for further evaluation."
  • #1
Albert1
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$f(x)$ is a real polynominal function with degree 100,and $f(k)=\dfrac {1}{k} , \,\,(k=1,2,3,4,5,------,101),$
please find $f(102)=?$
 
Last edited:
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  • #2
Albert said:
$f(x)$ is a real polynominal function with degree 100,and $f(k)=\dfrac {1}{k} \,\,(k=1,2,3,4,5,------,101),$
please find $f(102)=?$
hint:
set: $g(x)=xf(x)-1$
 
  • #3
Albert said:
$f(x)$ is a real polynominal function with degree 100,and $f(k)=\dfrac {1}{k} , \,\,(k=1,2,3,4,5,------,101),$
please find $f(102)=?$

take $g(x) = x f(x) - 1$
it is polynomial of degree 101 and zero for x = 1 through 101
so $g(x) = A (x-1)(x-2)\cdots(x-101)$
the constant term = $- A * 101! = -1$ so $A = \frac{1}{101!}$

so $g(x) = \frac{1}{101!} (x-1)(x-2)(x-3)\cdots(x-101)$
or $g(102) = 102 f(102) - 1 = -1 $ or $f(102) = 0$

above solution is incorrect the solution is

take $g(x) = x f(x) - 1$
it is polynomial of degree 101 and zero for x = 1 through 101
so $g(x) = A (x-1)(x-2)\cdots(x-101)$
the constant term = $- A * 101! = -1$ so $A = \frac{1}{101!}$

so $g(x) = \frac{1}{101!} (x-1)(x-2)(x-3)\cdots(x-101)$
or $g(102) = 102 f(102) - 1 = 1 $ or $f(102) = \frac{1}{51}$
 
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  • #4
kaliprasad said:
take $g(x) = x f(x) - 1$
it is polynomial of degree 101 and zero for x = 1 through 101
so $g(x) = A (x-1)(x-2)\cdots(x-101)$
the constant term = $- A * 101! = -1$ so $A = \frac{1}{101!}$

so $g(x) = \frac{1}{101!} (x-1)(x-2)(x-3)\cdots(x-101)$
or $g(102) = 102 f(102) - 1 = -1 $ or $f(102) = 0$
please check again $g(102)=?$
 
  • #5
Albert said:
please check again $g(102)=?$

oops
g(102) = 1 and I shall update the solution above
 

Related to Find the Value of $f(102)$ for $f(x)$ of Degree 100

1. How do you find the value of $f(102)$ for $f(x)$ of Degree 100?

The value of $f(102)$ for $f(x)$ of Degree 100 can be found by plugging in 102 for the variable x in the given equation and solving for f(x). This will give you the value of f(102).

2. Can the value of $f(102)$ be negative for $f(x)$ of Degree 100?

Yes, the value of $f(102)$ can be negative for $f(x)$ of Degree 100. The degree of a polynomial does not determine the sign of its value at a specific input. The sign is determined by the coefficients and the value of x.

3. Is finding the value of $f(102)$ for $f(x)$ of Degree 100 the same as finding the x-intercept?

No, finding the value of $f(102)$ for $f(x)$ of Degree 100 is not the same as finding the x-intercept. The x-intercept is the point where the graph of the function crosses the x-axis, whereas finding the value of $f(102)$ gives the output of the function at a specific input value.

4. Can the value of $f(102)$ for $f(x)$ of Degree 100 be a fraction?

Yes, the value of $f(102)$ for $f(x)$ of Degree 100 can be a fraction. The degree of a polynomial does not determine whether its values are fractions or not. It depends on the coefficients and the value of x.

5. What is the significance of finding the value of $f(102)$ for $f(x)$ of Degree 100?

Finding the value of $f(102)$ for $f(x)$ of Degree 100 is important because it helps us understand the behavior of the function at a specific input value. It can also be used to evaluate the function at other values close to 102 by using methods such as interpolation or extrapolation.

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