Question

arata ca nr 2^31×5^30+1 este nr compus ; 2^30×5^31+1 este nr compus.

Answer 1

$2^{31}* 5^{30}+1= 2^{1}* 2^{30}* 5^{30}+1=2*(2*5) ^{30}+1=2*10 ^{30} +1$ ≈ $2*10 ^{30}$

$2^{30}* 5^{31}+1= 2^{30}* 5^{30}* 5^{1}+1=(2*5) ^{30}*5+1=10 ^{30}*5 +1$$=5*10 ^{30}+1$ ≈ $5*10 ^{30}$