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← JEE Main 2026 · 4 Apr · Shift 2
MathematicsSingle correct+4 / -1Question 7 of 75

JEE Main 2026 · 4 Apr · Shift 2, Mathematics question 7

Let α=14+18+116+…∞\alpha=\dfrac14+\dfrac18+\dfrac1{16}+\dots\infty and β=13+19+127+…∞\beta=\dfrac13+\dfrac19+\dfrac1{27}+\dots\infty. Then the value of (0.2)log⁡5(α)+(0.04)log⁡5(β)(0.2)^{\log_{\sqrt5}(\alpha)}+(0.04)^{\log_5(\beta)} is equal to:

Choose one option
Answer and worked solution

Official answer: C

Sums. α=1/41−1/2=12\alpha=\frac{1/4}{1-1/2}=\frac12 and β=1/31−1/3=12\beta=\frac{1/3}{1-1/3}=\frac12.

First term. (0.2)log⁡5(1/2)=5−2log⁡5(1/2)=4(0.2)^{\log_{\sqrt5}(1/2)}=5^{-2\log_5(1/2)}=4.

Second term. (0.04)log⁡5(1/2)=5−2log⁡5(1/2)=4(0.04)^{\log_5(1/2)}=5^{-2\log_5(1/2)}=4.

Sum 8.

(C)