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1<br />
x tan<br />
1<br />
u tan<br />
x<br />
du 1<br />
<br />
dx 2<br />
1<br />
x<br />
dv<br />
x<br />
dx<br />
2<br />
x<br />
V <br />
2<br />
x<br />
2<br />
x 1<br />
tan<br />
2<br />
dx<br />
x<br />
<br />
<br />
2<br />
x 1 <br />
dx<br />
2 2<br />
1<br />
x <br />
(b) (i)<br />
2<br />
Q 16. (a) Evaluate<br />
dx<br />
x<br />
e 1<br />
let y = e x<br />
dy x<br />
(ii)<br />
e<br />
dx<br />
dy<br />
dxdx<br />
y<br />
y<br />
1<br />
(b) Find (i)<br />
(ii)<br />
x sec x dx<br />
<br />
3<br />
x<br />
dx<br />
2<br />
1<br />
x <br />
Solution<br />
(a)<br />
dx<br />
x<br />
e 1<br />
dx 1 dy <br />
<br />
x y<br />
e<br />
2<br />
x<br />
tan<br />
2<br />
2<br />
x<br />
tan<br />
2<br />
1<br />
1<br />
1<br />
x <br />
x <br />
<br />
<br />
y<br />
1<br />
dy<br />
y -1 <br />
1 1<br />
<br />
2 1 x<br />
x<br />
tan<br />
2<br />
<br />
y<br />
1<br />
<br />
2<br />
<br />
dx<br />
<br />
x C<br />
291<br />
<br />
y<br />
Let<br />
1<br />
1<br />
<br />
1 Ay B<br />
B 1<br />
<br />
A B<br />
<br />
y y 1<br />
y<br />
ln<br />
<br />
and<br />
<br />
y 1<br />
u = x<br />
du<br />
1<br />
dx<br />
dv<br />
sec<br />
dx<br />
v tan x<br />
A 1<br />
2<br />
dx<br />
2<br />
x<br />
ln e 1<br />
<br />
x<br />
e 1<br />
<br />
<br />
<br />
1<br />
1<br />
<br />
<br />
x<br />
x<br />
2<br />
e<br />
1<br />
ln e<br />
1 2<br />
1<br />
1.854587 0.541325 1<br />
0.3133 (4dps)<br />
2<br />
sec x<br />
dx<br />
2<br />
x<br />
2<br />
1<br />
= x tan x – (- ln cos x) + C<br />
= x tan x + ln cos x + C.<br />
3<br />
x<br />
dx<br />
<br />
2<br />
1 x<br />
Let x = sin u<br />
dx = cos u du<br />
3<br />
sin u<br />
cos<br />
u du<br />
<br />
<br />
2<br />
1<br />
sin u<br />
sin 3 u<br />
cos u du<br />
cos u<br />
<br />
<br />
<br />
sin 3 u du<br />
sin 2 u sin<br />
u du<br />
<br />
dy<br />
<br />
y 1 y<br />
<br />
<br />
1 1 <br />
dy<br />
y 1 y <br />
ln y 1 ln y<br />
<br />
x<br />
<br />
x<br />
e 1 ln e C<br />
ln<br />
<br />
x sec 2 x dx x tanx tan x . 1 dx