Question

Repedee dau coroana la ex 8

Answer 1

2^10 x 5^11+1=2^10 x 5^10 x5 +1=10^10 x5 +1
=1000....0(zece de 0) x 5 +1
=5000...0(zece de 0) +1
=5000....1  (sunt 9 de 0, pt ca in loc de ultimul 0 este 1))
suma cifrelor=5+1=6, => nr e divizibil cu 3, deci e nr compus

Answer 2

${2}^{10} \times {5}^{11} + 1 = 2 {}^{10} \times 5\times 5 {}^{10} \binom{}{deoarece \: 5are \: puterea1 \: iar \: 1 + 110 = 11 = > 5 \times 5 {}^{10} \: = {5}^{11} } = 10 {}^{10} \times 5 + 1 \\ = 10000...000 \binom{}{de \: 10 \: ori0} \times 5 + 1 \\ = 50000....00 \binom{}{de10 \: ori0} + 1 \\ = 50000000001 \binom{}{de \: 9ori \: 0} \\ = 5 + 0 + 1 = 6 \\ 6 \: est \: divizibil \: a \: mai \: multe \: nr. = > nr \: .este \: compus \:$