Find the 20th term of the AP whose 7th term is 24 less than the 11th term, first term being 12.


Let the a be first term and d be common difference


As we know


an = a + (n - 1)d


Given,


a7 = a11 - 24


a + 6d = a + 10d - 24


10d - 6d = 24


4d = 24


d = 6


given a = 12


then, a20 = a + 19d


a20 = 12 + 19(6)


= 12 + 114


= 126


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