Question

arata ca nr 4². 5 la puterea 5 a + 1 nu este prim​

Answer 1

$\displaystyle\it\\\\4^2\cdot5^5+1 = 2^4\cdot5^5+1=2^4\cdot5^4\cdot5=\\1\underbrace{0...00}_{de~4~ori}\cdot5+1=5\underbrace{0...00}_{de~4~ori}+1=5\underbrace{0...00}_{de~4~ori}1=\mathcal{M}_3,~\bigg(suma~cifrelor\bigg).\\asadar,~numarul~este~compus.$