Find the sum of the following AP:0.6, 1.7, 2.8,…, to 100 terms.

1.	Find the sum of the following AP:0.6, 1.7, 2.8,…, to 100 terms.
Answer» Given A.P : 0.6, 1.7, 2.8,…. S₁₀₀ a = 0.6; d = a₂ – a₁ = 1.7 – 0.6 = 1.1; n = 100 S_n = \(\frac{n}{2}\) [2a + (n – 1)d] ∴ S₁₀₀ = \(\frac{100 }{2}\) [2 × 0.6 + (100 – 1)1.1] = 50 [1.2 + 99 × 1.1] = 50 [1.2 + 108.9] = 50 × 110.1 = 5505

Answer»

Given A.P : 0.6, 1.7, 2.8,…. S₁₀₀

a = 0.6; d = a₂ – a₁ = 1.7 – 0.6 = 1.1; n = 100

S_n = \(\frac{n}{2}\) [2a + (n – 1)d]

∴ S₁₀₀ = \(\frac{100 }{2}\) [2 × 0.6 + (100 – 1)1.1]

= 50 [1.2 + 99 × 1.1]

= 50 [1.2 + 108.9]

= 50 × 110.1

= 5505

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