Find the sum of first 16 terms of the AP: 10, 6, 2…..
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Hey mate here is your answer,
Sum of first 16 terms of An Ap is = 8
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EXPLANATION.
A.P is 10,6,2,,,,,,,,,,,
As we know that,
First term of an ap = a = 10.
Common difference of an ap = d = b - a = c - b.
6 - 10 = 2 - 6.
-4.
Common difference = d = -4.
Formula of Sum of nth term of an ap.
⇒ Sₙ = n/2[2a + (n - 1)d].
⇒ S₁₈ = 18/2 [2(10) + (18 - 1)(-4)].
⇒ S₁₈ = 9[20 + 17(-4)].
⇒ S₁₈ = 9[20 - 68].
⇒ S₁₈ = 9[-48].
⇒ S₁₈ = -432.
MORE INFORMATION.
Supposition of terms in A.P.
(1) = Three terms as : a - d, a, a + d.
(2) = Five terms as : a - 2d, a - d, a, a + d, a + 2d.
(3) = Four terms as : a - 3d, a - d, a + d, a + 3d.
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