Thursday 17 December 2015

elementary number theory - Prove that for any integer $n$, if $b^2$ divides $n$, then $b$ divides $n$.




Prove that for any integer $n$, if $b^2$ divides $n$, then $b$ divides $n$.





Trying to figure out this proof. The proof I'm looking at is written as
$n$ = any integer, if $25|n \implies 5|n$.
I've been trying to figure this for days and have been running around in circles. Would appreciate a general proof for this.



$n$ = any integer, if $(b^2)|n \implies b|n$.


Answer



Use the definition: If $a \mid b \Rightarrow$ there is an integer $k$ such that $b=ak$.



So if $b^2 \mid n \Rightarrow$ there is an integer $k$ such that $n=b^2k= bbk$. Now the product of two integers is also an integer, setting $c = bk$, what can you conclude?


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