Let $x_1$ and $x_2$ be the two roots of equation $x^2 − 3x + 2 = 0$. Find the following values without computing $x_1$ and $x_2$ directly.

i) $x_1^4 + x_2^4$

ii) $x_1 - x_2$

(Note: for (i) above, how many different solutions can you find?)