1. x1=1, x2=0, x3=2
2. x1=5, x2=1, x3=−3
3. x1=13+11t, x2=2+5t, x3=t
4. x1=35+33t, x2=5+7t, x3=t
5. x1=13+4t, x2=6+t, x3=5+3t, x4=t
6. x1=17+t, x2=11+3t, x3=t, x4=−4
7. x1=3−8s+19t, x2=7+2s−7t, x3=s, x4=t
8. x1=−25+10s+22t, x2=s, x3=10−3t, x4=t
9. x1=1, x2=3, x3=−5, x4=6
10. x1=63s−16t, x2=13s−8t, x3=s, x4=5t, x5=t
11. x1=3, x2=−2, x3=4
12. x1=5, x2=−3, x3=2
13. x1=4+3t, x2=3−2t, x3=t
14. x1=5+2t, x2=t, x3=7
15. Inconsistent—no solution
16. Inconsistent—no solution
17. x1=3−2t, x2=−4+t, x3=5−3t, x4=t
18. x1=4+2s−3t, x2=s, x3=3−4t, x4=t
19. x1=3−s−t, x2=5+2s−3t, x3=s, x4=t
20. x1=2+3t, x2=1+s−2t, x3=2+2s, x4=s, x5=t
21. x1=2, x2=1, x3=3, x4=4
22. x1=3, x2=−2, x3=4, x4=−1
23. (a) None (b) k≠2 (c) k=2
24. (a) k≠2 (b) None (c) k=4
25. (a) k≠4 (b) k=4 (c) None
26. (a) All k (b) None (c) None
27. (a) None (b) k≠11 (c) k=11
28. No solution unless c=2a+3b, in which case it has infinitely many solutions.