If /6 /4 ( (x- 3 ) (x+ 3 )+1 )dx = e ( 3-1 ), then 9 2 is equal to .
Answer
12
Solution
(B-A)= A B+1 A- B
Take A=x- 3, B=x+ 3: B-A= 2 3, 2 3=- 1 3
A B+1=- 1 3 ( A- B )
I=- 1 3 /6 /4 [ (x- 3 )- (x+ 3 ) ]dx
=- 1 3 [ e | (x- 3 ) (x+ 3 ) | ] /6 /4
At x= 4: 15 105 = 3-1 3+1=2- 3; at x= 6: 30 90 = 12
I=- 1 3 e (2 (2- 3 ) )=- 1 3 e ( 3-1 )2=- 2 3 e ( 3-1 )
=- 2 3 9 2=9 43=12
Answer: 12