...
0dx)x(f
a
a
∫
−
=
. Hd: t=−x
125 ) Chứng minh rằng:
0xdxsinx
8
8
76
∫
π
π
−
=
. Áp dụng bài 124 ).
126 ) Chứng minh rằng:
∫∫
−
=
1
0
xcos
1
1
xcos
dxe2dxe
. Áp dụng bài 123 ).
127 ) Chứng minh rằng: Nếu ... y= 3 +
x
5
( x ≠ 0), ta có xy’ + y = 3
b) Với y = x sin x, ta có : xy – 2 ( y’ – sin x ) +xy” = 0
c) Với y = ( x +1 ) e
x
ta có : y’ – y = e
x
d) Với y= e
sin x
ta c...
... _______ are destroyed.
31. A. country B. planet C. society D. life
32. A. oxygen B. dioxide C. carbon D. ozone
33. A. poor B. developing C. European D. rich
34. a. risk B. danger C. accidents D. ... again. He is said to be immune to that disease. This means that his body has developed a
way of fighting the germs. However, people do not seem to become immune from colds. This fact puzzled the
s...