JEE MAIN - Mathematics (2019 - 11th January Evening Slot - No. 13)
If 19th term of a non-zero A.P. is zero, then its (49th term) : (29th term) is :
2 : 1
4 : 1
1 : 3
3 : 1
Explanation
a + 18d = 0 . . . . .(1)
$${{a + 48d} \over {a + 28d}} = {{ - 18d + 48d} \over { - 18d + 28d}} = {3 \over 1}$$
$${{a + 48d} \over {a + 28d}} = {{ - 18d + 48d} \over { - 18d + 28d}} = {3 \over 1}$$
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