The simplest approach to solving such questions is to try and come to a common base. Like write 4^28 in terms of the power of 2 which is the second term then you will have much clearer picture.
finally after 30 minutes figured out how to make heads or tails.
frist make base same
2^34-2^28
divide both by 2^28.
equals 2^6-2^0
=64-1=63.
find lcm of 63 which is 7,3,1.
hence, 7 is the greatest prime factor.
Khurram
