# NCERT Solutions class 12 Maths Exercise 7.9 (Ex 7.9) Chapter 7 Integrals

## NCERT Solutions for Class 12 Maths Exercise 7.9 hapter 7 Integrals – FREE PDF Download

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# NCERT Solutions for Class 12 Maths Chapter 7 Integrals (Ex 7.9) Exercise 7.9

Evaluate the definite integrals in Exercises 1 to 11.

1.

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=2 Ans.

2.

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3.

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4.

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5.

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= 0 Ans.

6.

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7.

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8.

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9.

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10.

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11.

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Evaluate the definite integrals in Exercises 12 to 20.

12.

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13.

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14.

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=150110x5x2+1dx+3011(5x)2+12dx=15∫0110x5x2+1dx+3∫011(5x)2+12dx

=15(log|5(1)2+1|log|5(0)2+1)+35(tan15–√tan10–√)=15(log⁡|5(1)2+1|−log⁡|5(0)2+1)+35(tan−15−tan−10)

=15(log6log1)+35(tan15–√0)=15(log⁡6−log⁡1)+35(tan−15−0)

=15(log60)+35(tan15–√0)=15(log⁡6−0)+35(tan−15−0)

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15.

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First we evaluate  =      ……….(i)

Putting

From eq. (i),  =

=

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16.

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(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),

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17.

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π41024+π2+2π41024+π2+2 Ans.

18.

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=

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19.

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20.

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[Applying Product Rule on first definite integral]

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Choose the correct answer in Exercises 21 and 22.

21.  equals:

(A)

(B)

(C)

(D)

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Therefore, option (D) is correct.

22.  equals:

(A)

(B)

(C)

(D)

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Therefore, option (C) is correct.