Solution
= Solution
The <rank-nullity theorem> states $\dim V=\dim\ker T+\dim\operatorname{im}T$ for a <linear map> from a finite-dimensional <vector space> $V$. Here the domain has dimension four and the <image> has dimension two. Thus \b[$\dim\ker T=4-2=2$]. For example, a <kernel> <basis> is $\{(-2,-1,1,0),(-1,-2,0,1)\}$, as follows from the reduced equations.