Saved Bookmarks
| 1. |
3. Is 144 a term of the A.P. 3, 7, 11slyFind the 20h term from the last term of the A.P. 3,8, 13,.,.253Reswill he 130 more than its 31st term? |
|
Answer» Given series is 3, 8, 13, ...... 253 here, first term , a = 3 common difference , d = 5 Let us find total number of terms at first.use => 253 = 3 + (n - 1)5 => 250 = 5(n - 1) => n - 1 = 50 => n = 51 so, there are 51 terms in given series.now we know, mth term from last =last term - mth term + 1 so, 20th term from last = 51 - 20 + 1 = 32 hence, 20th from last = 32th term from first T32=a+(32-1)duse , = 3 + 31 × 5 = 3 + 155 = 158 hence , 20th term from last = 158 |
|