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# NCERT Solutions for Class 12 Mathematics-II english Medium 7. Integrals

Page 9 of 12

## 7. Integrals

#### Exercise 7.9

Exercise - 7.9

Evaluate the definite integrals in Exercises 1 to 20

Ques.1.

Ans.

= 2

Ques.2.

Ans.

Ques.3.

Ans.

=

Ques.4.

Ans.

=

Ques.5.

Ans.

= 0

Ques.6.

Ans.

=

Ques.7.

Ans.

Ques.8.

Ans.

Ques.9.

Ans.

=

Ques.10.

Ans.

=

Ques.11.

Ans.  =

Ques.12.

Ans.

Ques.13.

Ans.  =

Ques.14.

Ans.

Ques.15.

Ans.

First we evaluate  =      ……….(i)

Putting

From eq. (i),  =

=

Ques.16.

Ans.

(On dividing)

where I =

……….(i)

Now, I =        ……….(ii)

Let          ……….(iii)

Comparing coefficients of      A + B = –20    ……….(iv)

Comparing constants     3A + B = –15   ……….(v)

On solving eq. (iv) and (v), we get   A =  B =

Putting these values in eq. (iii),

I =

Putting this value of I in eq. (i),

Ques.17.

Ans.

Ques.18

Ans.

Ques.19.

Ans.

Ques.20.

Ans.

[Applying Product Rule on first definite integral]

Choose the correct answer in Exercises 21 and 22.

Ques.21.  equals:

(A)

(B)

(C)

(D)

Ans.

=

hance, option (D) is correct.

Ques.22.  equals:

(A)

(B)

(C)

(D)

Ans.

hance, option (C) is correct.

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Page 9 of 12

## Topic Lists:

##### NCERT Solutions⇒Class 12th ⇒ Mathematics-II ⇒ Chapter 7. Integrals:

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