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← JEE Main 2026 · 2 Apr · Shift 2
MathematicsSingle correct+4 / -1Question 4 of 75

JEE Main 2026 · 2 Apr · Shift 2, Mathematics question 4

Let a1,a2,a3,…a_1,a_2,a_3,\dots be an A.P. and g1=a1,g2,g3,…g_1=a_1,g_2,g_3,\dots be an increasing G.P. If a1=a2+g2=1a_1=a_2+g_2=1 and a3+g3=4a_3+g_3=4, then a10+g5a_{10}+g_5 is equal to :

Choose one option
Answer and worked solution

Official answer: D

Unknowns. a1=g1=1a_1=g_1=1; let dd be the common difference and rr the common ratio.

Conditions. a2+g2=1+d+r=1a_2+g_2=1+d+r=1, so d=−rd=-r. a3+g3=1+2d+r2=4a_3+g_3=1+2d+r^2=4, so r2−2r−3=0r^2-2r-3=0; increasing G.P. means r=3r=3, d=−3d=-3.

Value. a10+g5=(1−27)+81=55a_{10}+g_5=(1-27)+81=55.

(D)