Inner Product: prove that $\langle w, v+v' \rangle = \langle w, v \rangle + \langle w, v' \rangle$

116 Views Asked by At

We could use linearity in the first argument, homogeneity in first argument, and conjugate symmetry properties of the dot product. So this was my attempt at proving this:

We know that $\langle v+v',w \rangle = \langle v, w \rangle + \langle v',w \rangle$ and we also know that $\langle v,w \rangle = \overline{\langle w,v \rangle}$ (conjugate). Therefore

$\langle v+v',w \rangle = \overline{\langle w, v+v' \rangle}$

$\langle v+w \rangle + \langle v'+w \rangle = \overline{\langle w,v \rangle}+ \overline{\langle w+v' \rangle}$

Then $\overline{\langle w, v+v' \rangle}= \overline{\langle w,v \rangle}+ \overline{\langle w+v' \rangle}$

and taking the conjugate ${\langle w, v+v' \rangle}={\langle w,v \rangle}+ {\langle w+v' \rangle}$

Not sure if my argument makes sense (I'm not very familiar with conjugates)

1

There are 1 best solutions below

0
On BEST ANSWER

$$\begin{align*} \langle w,v+v' \rangle &= \overline{\langle v+v',w \rangle}\\ &= \overline{\langle v,w \rangle + \langle v',w \rangle}\\ &= \overline{\langle v,w \rangle} + \overline{\langle v',w \rangle}\\ &= \langle w,v \rangle + \langle w,v' \rangle \end{align*}$$