Will you integrate it 2015 times? - I

Calculus Level 2

A function f : R R f : \mathbb{R} \rightarrow \mathbb{R} is differentiated 2015 times to get g ( x ) = d 2015 d x 2015 [ f ( x ) ] g(x) = \dfrac{ d^{2015} }{dx^{2015} } \big[ f(x) \big] .

True or False

If g ( x ) = 0 g(x) = 0 for all values of x x , then f ( x ) f(x) has to be a polynomial.


This problem is part of the set - Will you integrate it 2015 times?
False True

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Pranshu Gaba
Nov 11, 2015

Let f ( n ) ( x ) f ^{ (n) } (x) denote the n n th derivative of f ( x ) f(x) with respect to x x .

We are given that g ( x ) = f ( 2015 ) ( x ) = 0 g(x) = f^{(2015)} (x) = 0 for all x x . After integrating it once, we get f ( 2014 ) ( x ) = c 1 f^{ (2014 ) } (x) = c_{1} , where c 1 c_{1} is the constant of integration.

Integrating it again, we get f ( 2013 ) ( x ) = c 1 x + c 2 f^{ (2013) } (x) = c_{1} x + c_{2} , where c 2 c_{2} is the constant of integration. After integrating it a total of 2015 2015 times, we get

f ( x ) = c 1 x 2014 + c 2 x 2013 + c 3 x 2012 + + c 2014 x + c 2015 f(x) = c_{1} x^{2014} + c_{2} x^{2013} + c_{3} x^{2012} + \cdots + c_{2014} x + c_{2015}

Here, c i c _{i} 's can be any real numbers. However, note that f ( x ) f(x) is always a polynomial. Therefore the statement "If g ( x ) = 0 g(x) = 0 for all values of x x , then f ( x ) f(x) has to be a polynomial." is True \boxed{ \text{True} } . _\square

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...