Question

d the sum of the following
(i) 2,7,12, ..., to 10 terms.​

Answer 1

$\sf{2, 7, 12,..,to\: 10 term\:}$

$\sf{We \:know \:that\:}$

$=</p><p>(2a \: + \: (n - 1) \: d) \: 2$

${ \:n = 10,\: a = 2,\:}$

$d = 7 - 2 = 2$

$\sf{Putting \:these \:in \:formula,\:}$

$(2a \: + \: (n - 1) \: d)$

$10 \: (2 \times 2 + (10 - 1) \times 5)$

$= 5(3 + 9 \times 5)$

$5 \: (4 + 45)$

$= 5(49)$

$= 245$