IIT JEE , AIEEE Forum - Mathematics , Algebra

sandeepramesh

106. A = $(4^{673} + 673^4)$ , B = $(4^{929} + 929^4)$
Are A and B prime?

No one who has seen this soln shd answer esp nadeem and hsbhatt(if uve seen it posted by madness)

bsgdabest

Both A and B end wtih unit digit=5, so both are multiples of 5..they are not prime
proof:
4^1 ends in 4
4^2 ---------6
4^3-----------4 so it repeats for every 2 powers of integers which differ by 2, similiarly powers of 3 repeat for 4 such types if integers, so we get both A and B to end in 5

hsbhatt

sophie germain is rising from her grave. but i havent seen ur soln. is it in mathlinks?

sandeepramesh

hsbhatt ur method is more elegant but i told ya not to reply

hsbhatt

just gave a crossword clue yaar

sandeepramesh

bsgdabest what if i change the ques to

A = $(4^{673} + 675^4)$ , B = $(4^{929} + 925^4)$
Are A and B prime?

Dont answer this hsbhatt!

Yes its in mathlinks posted by nadeem moidu, though i told him not to too

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