10th CBSE math solution for exercise 5.2 part 2

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

10th CBSE math solution for exercise 5.2 part 2

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

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

Solution:

a = 10  d = a - 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 = a - 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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