If the integral above is equal to , where and are integers, find .
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.
Let f ( x ) = x 3 sec 2 x . Then f ( − x ) = ( − x ) 3 sec 2 ( − x ) = − ( x 3 sec 2 x ) = − f ( x ) . Therefore the function is odd and since the function is defined for x ∈ [ − 4 π , 4 π ] the integral is equal to 0 .
We need to find two integers A and B such that π A − B = 0 , and the only way for this to be possible is if A = 0 (any other integer will include pi), and therefore B = 1 .
Therefore A + B = 0 + 1 = 1 .