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  1. J

    Theorems every mathematician should know

    Let's compile a list of theorems we think every mathematician ought to know! I'll start: Stoke's Theorem: If M is a smooth n-dimensional manifold, and \omega is a compactly supported (n-1) form on M, then \int_{M} d\omega = \int_{\partial M} \omega
  2. J

    Has this equation got a solution?

    Actually, let me clarify: Let R be the space of real numbers. R x R (pronounced "R cross R") is the set of all ordered pairs (x,y) where x and y are both in R. When you graph a function f(x) = ???, you are looking at every x and finding the unique y value that lies above it. In fact, the...
  3. J

    Has this equation got a solution?

    This is what you are looking for: The solution is x = 1, but it depends on how you make your definitions. If you define the square root to be a relation instead of a function, you can say that sqrt(1) is both 1 and -1.
  4. J

    Recognize a product of two vars in Mathematica?

    In your case, the simplest thing to do is replace (R*W) with some variable (say t). Then you just take Limit[x*t^2 + 4*x, t -> 0]. In your example you are only really taking a one dimensional limit, after all. If you do need to take a multidimensional limit, you say: Limit[x*(R*W)^t + 4*x...