If = 122 -1x2x2-3x+2 dx, then the value of 7 ( 2 7 ) is . (Here, the inverse trigonometric function -1x assumes values in (- 2, 2 ).)
Answer
21
Solution
Put x 1x: dx - dxx2 and 2x2-3x+2 2-3x+2x2x2, so = 1/22 -1(1/x)2x2-3x+2dx.
Add: 2 = 2 1/22 dx2x2-3x+2 (as -1x+ -1 1x= 2 for x>0).
dx2 [(x- 34)2+ 716 ]= 2 7 -1 4x-3 7; limits give 2 7 [ -1 5 7+ -1 1 7 ]= 2 7 -1(3 7) (since 6/ 71-5/7=3 7).
= 4 2 7 -1(3 7) 2 7 = -1(3 7).
7 ( 2 7 )= 7 3 7=21
Answer: 21