A) Thrice of
B) Twice of
C) Half of
D) Equal to
Correct Answer: B
Solution :
Let 1st term of A.P. be a and common difference be d. Now,\[{{a}_{9}}=0\Rightarrow a+8d=0\Rightarrow a=-8d\] ...,(i) Now, \[{{a}_{29}}=a+28d=-8d+28d\] \[\Rightarrow \] \[{{a}_{29}}=20d\] of ....(ii) Also, \[{{a}_{19}}=a+18d=-8d+18d=10d\] \[\Rightarrow \] \[2\times {{a}_{19}}=2\times 10d=20d\] ....(iii) From (ii) and (iii), we have \[{{a}_{29}}=2\,\,{{a}_{19}}\]
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