Making a eigenvector a linear combination of other eigenvectors

JordanGo
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Homework Statement


Write the eigenvector of \sigmax with +1 eigenvalue as a linear combination of the eigenvectors of M.


Homework Equations



\sigmax = (0,1),(1,0) (these are the columns)

The Attempt at a Solution



... Don't know what to do. Can someone show me how to do this using arbitrary eigenvectors, say (a,b) and (c,d)?
 
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Can you find the eigenvector in question? Let's denote it by (v,w). Then you can write
(v,w) = C1(a,b) + C2(c,d) and solve the constant C's.
 
Ok, that makes sense, thanks a lot!
 
JordanGo said:

Homework Statement


Write the eigenvector of \sigmax with +1 eigenvalue as a linear combination of the eigenvectors of M.


Homework Equations



\sigmax = (0,1),(1,0) (these are the columns)
Okay, that's \sigma. What is M? we can't write something "as a linear combination of the eigenvectors of M without knowing what M is!

The Attempt at a Solution



... Don't know what to do. Can someone show me how to do this using arbitrary eigenvectors, say (a,b) and (c,d)?
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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