Question

find th sum of first 10 terms of the AP 8,10,12​

Answer 1

$Medium</p><p></p><p>ANSWER</p><p></p><p>The \: sum \: of \: last ten \: terms \: of \: the \: AP: \:  8,10,12,...,126  \: is \: same \: as \: the \: sum \: of \: first \: ten \: terms \: of \: the \: AP:  \: 126,124,122,...,8.</p><p>Therefore, \:  a=126,d=−2 and n=10. \: </p><p>Now,  \: S10=210 \: [2×126+(10−1)×−2] \: </p><p>⇒S10 \: =5×[252−18]=1170 \: </p><p></p><p></p><p>$