I have to create an orthonormalbasis $\{b_1,b_2,b_3\}$ of the $\Bbb R^3$ with the vectors $a=(-1,1,2),\ b=(-2,0,0),\ c=(3,3,1)$
I know how to do that since there is Gram Schmidt but the exercise gives an extra information that confuses me:
$\begin{aligned}\operatorname{span}\{b_1\}&=\operatorname{span}\{a\} \\\operatorname{span}\{b_1,b_2\}&=\operatorname{span}\{a,b\}\\ \operatorname{span}\{b_1,b_2,b_3\}&=\operatorname{span}\{a,b,c\}\end{aligned}$
Can someone help?