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Re: Help with Identities
dear sir the reason maybe Mathematica does not know the x and y greater than 0 or not. so you must assuming the x and y greater than 0; and more over, the log doesn't smarter than man. so you must tell the Mathematica to do it using the function FullSimplify or Simplify; and then, FullSimplify[Log[x/y] == Log[x] - Log[y], x > 0 && y > 0] NOTE is two == and return true; but if you use === ans it will return false, because the header is different i think; But if you use this Assuming[x > 0 && y > 0, Log[x/y] === FullSimplify[Log[x] - Log[y]]] telling the Mathematica the x and y greater than 0 first, you can get the result true both use == and === i hope this will hope you. you also can test Sin[2 x] == 2 Sin[x] Cos[x]; without Simplify you will get nothing.