hi! what is the easiest way to prove that the set A is closed and the set B is not closed? 1). A={(x,y) ∈ R²: x²+y²=1} and 2). B={(x,y) : ∈ R²: x² - y²=1} Help please. thanks please
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Originally Posted by sorv1986 hi! what is the easiest way to prove that the set A is closed and the set B is not closed? 1). A={(x,y) ∈ R²: x²+y²=1} and 2). B={(x,y) : ∈ R²: x² - y²=1} Help please. thanks please I mean, the easiest way would be to note that , is continuous (it's just a polynomial) and and for the second one are you sure it isn't closed?
oho....actually the 2nd one i think its a hyperbola...so it should be not closed...am i wrong?.....but in the first case...i did not understand what r u actually doing to prove that set A is closed
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