JEE Main 2025 Mathematics question
Let a1, a2, a3..... be a G.P. of increasing positive terms. If a1a5 = 28 and a2 + a4 = 29, then a6 is equal to
Answer: (3)
Solution
a²r⁴=28 and ar(1+r²)=29. Solving gives r=√28, a=1/√28, so a6=ar⁵=784.
Let a1, a2, a3..... be a G.P. of increasing positive terms. If a1a5 = 28 and a2 + a4 = 29, then a6 is equal to
a²r⁴=28 and ar(1+r²)=29. Solving gives r=√28, a=1/√28, so a6=ar⁵=784.