Prove that, if n is an integer and n REM 4 = 2, then is not a perfect square

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So far I have, given that n is an integer we have integers q,b and r such that n = q x b + r. We know N REM 4 = 2. what is the next step?

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Argue by way of contradiction. Suppose that $n=m^2$. Now apply the division algorithm to $m,4$ to get $$m=4q+r$$ where $r=0,1,2,3$. We square $m$ to get $$n=m^2=(4q+r)^2=16q^2+8qr+r^2$$ Now consider each of the four possibilities for $r$, and determine that the result can never be $4k+2$, for integer $k$.