For finding, the sum of last ten terms, we write the given AP in reverse order i.e, 126, 124, 122,..., 12, 10, 8
Hence,first term (a) = 126, common difference, (d) = 124 - 126
So, [tex]S _{10} = \frac{10}{2} [ 2a + (10 - 1)d ] \: [/tex]
[tex] = 5 [2(126) + 9( - 2) ] [/tex]
[tex] = 5(252 - 18)[/tex]
[tex] = 5 \times 234 = 1170[/tex]
