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18
Prove that $A=\left(\begin{array}{ccc}1&2&3\\4&5&6\\7&8&9\end{array}\right)$ is not invertible
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17
Funny identities
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16
Real life applications of Topology
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10
Can every closed subset of real numbers be written as the countable (or finite) union of disjoint closed intervals?
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9
Variety vs. Manifold
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9
Decide for which positive values on a that makes the series converge
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8
Proving $\frac{x}{x^2+1}\leq \arctan(x)$ for $x\in [0,1].$
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8
What is the conjugate of $\frac{1}{2}+ \frac{3}{2}i$?
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8
Define $\lim_{x\rightarrow 0} \frac{1}{x}\int_{0}^{x} e^{t^{2}} dt$, what is the purpose of this question?
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8
Proving $(x^2)^{-1} = (x^{-1})^2$ in context of group theory.
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7
Why is the tensor algebra of a vector space non-commutative?
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6
How quickly with better tool
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6
A maze about $\pi$.
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6
Are torsion modules always finite?
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5
How to calculate $\displaystyle\lim_{x \to \infty} \left ( \frac{x+2}{x} \right )^{x}=e^{2}$
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5
List of Interesting Math Videos/ Documentaries
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5
Cohomology ring of a product
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5
Mathematical reason for the validity of the equation: $S = 1 + x^2 \, S$
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5
Null-homotopy of a map to the circle
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5
What are the most common errors in math exams: when is asked to study the function f(x)=…?
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5
Is it possible to have a fraction wherein the numerator and denominator are also fractions?
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5
Meaning of the phrase “Limit does not exist”.
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5
well-defined functions
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5
a question on symmetric group $S_5$
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5
Why are epsilon-delta proofs difficult?
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5
Integral of $\sin (2x)/(1+\cos^2 x)$
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5
What is the rank of a matrix for?
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