Do you know its Property-3
Algebra
Level
5
\( a_n\) is the nth term of an increasing arithmetic progression. If \[\sum_{r=1}^{4000}\frac{1}{a_r a_{r+1}}=10\] and \(a_{2001}=25\), what is the value of \( |a_1-a_{4001}|\)?
You can try more such problems of the set Do you know its property ?
by
Sanjeet Raria