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Oct
22
revised Find an orthonormal basis for W and $W^{\perp}$
fixed LaTex formatting
Oct
22
revised L'Hospital's Rule to find limit
cleaned up formatting and presentation
Oct
22
awarded  Enlightened
Oct
22
awarded  Nice Answer
Oct
22
reviewed Approve L'Hospital's Rule to find limit
Oct
22
answered Whether a matrix is a zero matrix
Oct
21
answered Find basis of 4x3 Matrix
Oct
21
answered Algebraic Proofs in Combinatotics
Oct
16
answered Solve $\sqrt{3x}+\sqrt{2x}=17$
Oct
15
comment Proving or disproving A+B is invertible
@anderstood: You're absolutely right. My nitpick was a (very, very minor) aesthetic one, not a critique of the actual content.
Oct
15
awarded  Yearling
Oct
14
comment Proving or disproving A+B is invertible
And now you have a second proof that $AB \neq BA$ for your specific example! ;) Small nitpick: if we're assuming $A$ is $k$-nilpotent, then the sum in your formula needs only to run from $i = 0$ to $i = k - 1$.
Oct
14
answered Proving or disproving A+B is invertible
Oct
14
answered A question about Klaus Hulek algebraic geometry
Oct
14
revised What is the ratio between the speed of the boat and speed of the water current?
edited tags
Oct
12
comment Is it true that $\langle a+cb, a+cb\rangle = \langle a,a\rangle + c^2 \langle b,b\rangle $ where $a,b \in \mathbb{R}^n$ and $c \in \mathbb{R}$?
It's not true in general. You need either $c = 0$ or $\langle a, b \rangle = 0$.
Oct
12
answered Game Theory - First move vs second move advantage?
Oct
11
answered Definition of equivariant map if one of the actions is a right action
Oct
6
comment Tom can choose from $4$ soups, $5$ salads and $4$ drinks for his lunch. How many different combinations of a soup, a salad, and a drink can he make?
Tom should go with French onion, Caesar, and water, and ignore any other combination. (But see Farzad's answer to see how many combinations he's excluding.)
Oct
6
answered how do we know that the rank of AB will be less than a number?