Prove the statements in $12,18,28,32,38,55,60$

for $\{$:$2n4,n^2$:$)=2^n$

If $n$ is an even integer, then $n^2-1$ is odd

If $x^2+2x-3=0,$ then $x2(!=$ is "not equals"$)$

If the product of two integers is not divisible by an integer $n,$ then neither integer is divisible by $n$

The difference of two consecutive cubes is odd

The sum of an integer and its cube is even

If $n$ is a positive integer that is a perfect square, then $n+2$ is not a perfect square. $($Perfect square $==$ the square root is an integer$)$