(-\frac{x}{2}+6)(6+\frac{x}{2})=4-(4-\frac{x}{2})^2
(6-\frac{x}{2})(6+\frac{x}{2})=4-(16-\not8^4*\frac{x}{\not2^1}+(\frac{x}{2})^2)
36-(\frac{x}{2})^2=4-(16-4x+\frac{x^2}{4})
36-\frac{x^2}{4}=4-16+4x-\frac{x^2}{4}
-\frac{x^2}{4}-4x+\frac{x^2}{4}=-12-36
-4x=-48/:(-4)
x=12
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