1.

The sum of first 10 terms of an Arithmetic Progression is 55 and the sum of first 9 terms of the same arithmetic progression is 45. Then its 10 term is​

Answer»

Answer:

10

Step-by-step explanation:

  For first 10 terms:

⇒ 1st term + 2nd term + 3rd term + ... 10TH term

⇒ sum of first 9 term + 10th term

    Given, S₉ = 45, S₁₀ = 55

⇒ S₁₀ = S₉ + T₁₀

⇒ 55 = 45 = T₁₀

⇒ 10 = T₁₀

 Hence the 10th term is 10

                  Technique 2:

S₁₀ = (10/2)[2a + 9d] = 10a + 45d = 55

S₉ = (9/2)[2a + 8d] = 9A + 36D  = 45  

 SOLVING these equations, we get

a = 1, and d = 1

 Hence 10th term = a + 9d

             = 1 + 9(1) = 10


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