The sum of 1st, 3rd and 17th term of an ap is 216. Find the sum of the 13 terms of the A.P?
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The sum of 1st, 3rd and 17th term of an ap is 216. Find the sum of the 13 terms of the A.P?
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936
Step-by-step explanation:
Hi,
Given that the sum of first, third and seventeenth terms of an AP is 216
Let the first term of AP be 'a'
Let the common difference of the A.P be 'd'
T₁ = a
T₃ = a + 2d
T₁₇ = a + 16d
T₁ + T₃ + T₁₇ = 216
3a + 18d = 216
a + 6d = 72
T₇ = 72
Sum of first 13 terms of A.P
= 13/2[2a + 12d]
= 13*T₇
= 13*72
= 936
Hope, it helps!
Answer:
936
Please see the attached image for explanation