Find the 20 term for from the last term of the AP 3 8 13 253

1.	Find the 20 term for from the last term of the AP 3 8 13 253
Answer» Given series is 3, 8, 13, ...... 253here, first term , a = 3common difference , d = 5Let us find total number of terms at first.use\xa0=> 253 = 3 + (n - 1)5=> 250 = 5(n - 1)=> n - 1 = 50=> n = 51so, there are 51 terms in given series.now we know, mth term from last =last term - mth term + 1so, 20th term from last = 51 - 20 + 1 = 32hence, 20th from last = 32th term from firstuse ,\xa0= 3 + 31 × 5 = 3 + 155 = 158hence , 20th term from last = 158 158 98

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