1. x(t)=73, y(t)=−83
2. x(t)=18(1+12t), y(t)=−14(5+4t)
3. x(t)=1756(864e−t+4e6t−868+840t−504t2), y(t)=1756(−864e−t+3e6t+861−882t+378t2)
4. x(t)=184(99e5t−8e−2t−7et), y(t)=184(99e5t+48e−2t−63et)
5. x(t)=13(−12−e−t−7te−t), y(t)=13(−6−7te−t)
6. x(t)=−1256(91+16t)et, y(t)=132(25+16t)et
7. x(t)=1410(369et+166e−9t−125 cos t−105 sin t), y(t)=1410(369et−249e−9t−120 cos t−150 sin t)
8. x(t)=13(17 cos t+2 sin t), y(t)=13(3 cos t+5 sin t)
9. x(t)=14(sin 2t+2t cos 2t+t sin 2t), y(t)=14t sin 2t
10. x(t)=113et(4 cos t−6 sin t), y(t)=113et(3 cos t+2 sin t)
11. x(t)=12(1−4t+e4t), y(t)=14(−5+4t+e4t)
12. x(t)=t2, y(t)=−t2
13. x(t)=12(1+5t)et, y(t)=−52tet
14. x(t)=18(−2+4t−e4t+2te4t), y(t)=12t(−2+e4t)
15. (a) x1(t)=200(1−e−t/10), x2(t)=400(1+e−t/10−2e−t/20) (b) x1(t)→200 and x2(t)→400 as t→+∞ (c) Tank 1: about 6 min 56 s; tank 2: about 24 min 34 s
16. (a) x1(t)=600(1−e−t/20), x2(t)=300(1+e−t/10−2e−t/20) (b) x1(t)→600 and x2(t)→300 as t→∞ (c) Tank 1: about 8 min 7 sec; tank 2: about 17 min 13 sec
17. x1(t)=102−95e−t−7e5t, x2(t)=96−95e−t−e5t
18. x1(t)=68−110t−75e−t+7e5t, x2(t)=74−80t−75e−t+e5t
19. x1(t)=−70−60t+16e−3t+54e2t, x2(t)=5−60t−32e−3t+27e2t
20. x1(t)=3e2t+60te2t−3e−3t, x2(t)=−6e2t+30te2t+6e−3t
21. x1(t)=−e−t−14e2t+15e3t, x2(t)=−5e−t−10e2t+15e3t
22. x1(t)=−10e−t−7te−t+10e3t−5te3t, x2(t)=−15e−t−35te−t+15e3t−5te3t
23. x1(t)=3+11t+8t2, x2(t)=5+17t+24t2
24. x1(t)=2+t+ ln t, x2(t)=5+3t−1t+3 ln t
25. x1(t)=−1+8t+ cos t−8 sin t, x2(t)=−2+4t+2 cos t−3 sin t
26. x1(t)=3 cos t−32 sin t+17t cos t+4t sin t, x2(t)=5 cos t−13 sin t+6t cos t+5t sin t
27. x1(t)=8t3+6t4, x2(t)=3t2−2t3+3t4
28. x1(t)=−7+14t−6t2+4t2 ln t, x2(t)=−7+9t−3t2+ ln t−2t ln t+2t2 ln t
29. x1(t)=t cos t−(ln cos t)(sin t), x2(t)=t sin t+(ln cos t)(cos t)
30. x1(t)=12t2 cos 2t, x2(t)=12t2 sin 2t
31. x1(t)=(9t2+4t3)et, x2(t)=6t2et, x3(t)=6tet
32. x1(t)=(44+18t)et+(−44+26t)e2t, x2(t)=6et+(−6+6t)e2t, x3(t)=2te2t
33. x1(t)=15t2+60t3+95t4+12t5, x2(t)=15t2+55t3+15t4, x3(t)=15t2+20t3, x4(t)=15t2
34. x1(t)=4t3+(4+16t+8t2)e2t, x2(t)=3t2+(2+4t)e2t, x3(t)=(2+4t+2t2)e2t, x4(t)=(1+t)e2t