Math, asked by AvniPrasad3802, 1 year ago

the sum of n term of an AP is [5n2/2+3n/2].find the 20th term.

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Answered by HappiestWriter012
597
Sum of n terms =[ 5n²/2 + 3n/2 ]

Sum of 1 term = 5*1/2 + 3(1)/2 = 8/2 = 4 .

Sum of two terms = 5(4)/2 + 3(2)/2 = 10+3 = 13 .

Second term = 13 - 4 = 9 .

Common difference = 9 - 4 = 5 .

20 th term = a + ( 20 - 1 )d = a+19d = 4 + 19(5) = 99 .

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Answered by rahul475567
99

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