Question

we have,
( 13, a_{1}, a_{2}, a_{3}--67 ) are in ( A . P )
( therefore a_{1}+a_{2}+a_{3}+ldots+a_{20}=20left(frac{13+16}{2}right)=800 )
Now ( A M geqslant G M )
Or ( a, a_{2} a_{3}-a_{20} leq(40)^{20} )
: Fhax value of ( a_{1} a_{2}-a_{20} )
is ( (40)^{20} )
Regards

# 172. Ifa, az, az, ........., a 20 are A.M.s between 13 and 67, then the maximum value of 01.02. az ...........azo is (A) (20)20 (B) (40)20 (C) (60)20 (D) (80)20

Solution