Question

write the algebra of 10,18,26,calculate the sum of first 30 terms​

Answer 1

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write the algebra of 10,18,26,calculate the sum of first 30 terms

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$\longmapsto\tt{Series = 10, 18, 26}$

$\longmapsto\tt{First \: \: term = a1 = 10}$

$\longmapsto\tt{common \: \: difference = 18 - 10 = 8}$

$\longmapsto\tt{Find \: the \: nth \: term:}$

$\longmapsto\tt{an = a1 + (n - 1)d}$

$\longmapsto\tt{an = 10 + (n - 1)8}$

$\longmapsto\tt{an = 10 + 8n - 8}$

$\longmapsto\tt{an = 2 + 8n}$

$\longmapsto\tt{Find \: the \: 30th \: term:}$

$\longmapsto\tt{a30 = 2 + 8(30)}$

$\longmapsto\tt{a30 = 242}$

$\longmapsto\tt{Find \: the \: sum \: of \: the \: first \: 30 \: terms:}$

$\longmapsto\tt{sn = n/2 (a1 + an)}$

$\longmapsto\tt{s30 = 30/2 (10 + 242) = 3780}$

$\longmapsto\tt{3780}$