[tex]\bf x-y=xy\impliedby \textit{product rule on the right-hand-side}
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1-\cfrac{dy}{dx}=1\cdot y+x\cdot \cfrac{dy}{dx}\implies 1-\cfrac{dy}{dx}=y+x \cfrac{dy}{dx}
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1-y=\cfrac{dy}{dx}+x\cfrac{dy}{dx}\impliedby \textit{now, we take common factor}
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1-y=\cfrac{dy}{dx}(1+x)\implies \cfrac{1-y}{1+x}=\cfrac{dy}{dx}[/tex]
