defence exam Coast Guard Navik GD (General Duty) 02/2025 Mock Test Series Mathematics Sequences and Series Geometric Progressions
Let a1, a2, a3, … be a G.P. such that a1 < 0, a1 + a2 = 4 and a3 + a4 = 16. If \(\sum_{i=1}^9 a_i=4 \lambda\) then λ is equal to :
1
171
2
511/3
3
-171
4
-513