CBSE Class 12 Math 2020 Delhi Set 2 Solved Paper

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Question : 7
Total: 11
Find
x+1
x(12x)
dx
Solution:  
Let
I=
x+1
x(12x)
dx

Also, let
Also, let
x+1
x(12x)
=
A
x
+
B
12x

x+1
x(12x)
=
A(12x)+Bx
x(12x)

x+1=x(2A+B)+A
Comparing coefficient of x both sides, we get
1=2A+B
Comparing constant term both sides, we get
A=1
From equation (i),
1=2(1)+B
B=3
x+1
x(12x)
dx
=
1
x
dx
+
3
12x
dx

=log|x|+
3log|12x|
2
+C

=log|x|
3
2
log
|12x
|+C Ans.

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