This page 10th CBSE math solution for exercise 5.2 part 2 is going to provide you solution for every problems that you find in the exercise no 5.2 part 1

(2) Choose the correct choice in the following and justify

(i) 30th term of the AP: 10,7,4,....... is

Solution:

a = 10 d = a₂ - a ₁

= 7 - 10

= -3

a n = a + (n - 1 ) d

= 10 + (30 - 1) (-3)

= 10 + 29 (-3)

= 10 - 87

= -77

So option C is correct

(ii) 11th term of the AP -3,-1/2,2,.......... is

(A) 28 (B) 22 (C) -38 (D) -48 **½**

Solution:

a = -2 d = a₂ - a ₁ n = 11

= -1/2 - (-3)

= (-1/2) + 3

= (-1 + 6)/2

= 5/2

a n = a + (n - 1 ) d

= -3 + (11 - 1) (5/2)

= -3 + 10 (5/2)

= -3 + 25

= 22

So option B is correct

(3) In the following APs, find the missing term in the boxes

(i) 2, ____ , 26

a ₁ = 2 a₃ = 26

from this we need to find the value of a ₂

a₃ = 26

a + 2 d = 26

2 + 2 d = 26

2 d = 26 - 2

2 d = 24

d = 24/2

d = 12

a ₂ = a + 1 d

= 2 + 1 (12)

= 2 + 12

= 14

Therefore the second term is 14

(ii) ____, 13 , ___ , 3

Solution:

a ₂ = 13

a₄ = 3

a + d = 13 --------(1)

a + 3 d = 3 --------(2)

(1) - (2)

a + d = 13

a + 3 d = 3

(-) (-) (-)

--------------

- 2 d = 10

d = 10/(-2)

d = -5

Substitute d = -5 in the first equation

a + d = 13

a - 5 = 13

a = 13 + 5

a = 18

First term = 18

Third term = a + 2 d = 18 + 2 (-5)

= 18 - 10

= 8

Third term = 8

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