Need help with #3

3. Let A be a particular vector in R22. Determine whether the following are subspaces of R22 and justify your answers. (a) S1={BR22:BA=0} (b) S2={BR22:AB=BA} (c) S3={BR22:AB+B=0} 4. Which of the sets that follow are spanning sets for R3 ? Justify your answers. (a) {(1,0,0)T,(0,1,1)T,(1,0,1)T} (b) {(1,0,0)T,(0,1,1)T,(1,0,1)T,(1,2,3)T} (c) {(2,1,2)T,(3,2,2)T,(2,2,0)T}