Using PMI, prove that
52n+2-24n-25 is divisible by 576 for n belongs to N.
let p (n ) = 52n+2-24n-25
p(1) = 54 - 24 -25 = 576 -------- true
assume p(k) = 52k+2 - 24k - 25 is true
=> 52k+2 - 24k - 25 = 576 x c where c is some constant
=> 52k x 52 = 576c + 24k + 25 ------------ 1
to prove : p ( k+1) is true ie... 52k+4 - 24 - 24k - 25 is div by 576
52k+4 - 24 - 24k - 25 = 52k x 52 x 52 - 24k -49
= ( 576c + 24k + 25 )52 - 24k - 49 since 52k x 52 = 576c + 24k + 25
= 576 x 25 c + 25 x 24 k + 625 -24k - 49
= 576 x 25c + 24k ( 25-1) +576
= 576 x 25c + 24k x 24 + 576
= 576 ( 25c + k + 1 ) which is a multiple of 576
therefore p( k+1 ) is true
by MI 52n+2-24n-25 is divisible by 576 for n belongs to N.