1. y(x)=c0(1+x+x22+x33!+⋯)=c0ex; ρ=+∞
2. y(x)=c0(1+4x1!+42x22!+43x33!+44x44!+⋯)=c0e4x; ρ=∞
3. y(x)=c0(1−3x2+(3x)22!22−(3x)33!23+(3x)44!24−⋯)=c0e−3x/2; ρ=+∞
4. y(x)=c0(1−x21!+x42!−x63!+⋯)=c0e−x2; ρ=∞
5. y(x)=c0(1+x33+x62!32+x93!33+⋯)=c0exp(13x3); ρ=+∞
6. y(x)=c0(1+x2+x24+x38+x416+⋯)=2c02−x; ρ=2
7. y(x)=c0(1+2x+4x2+8x3+⋯)=c01−2x; ρ=12
8. y(x)=c0(1+x2−x28+x316−5x4128+⋯)=c01+x−−−−−√; ρ=1
9. y(x)=c0(1+2x+3x2+4x3+⋯ )=c0(1−x)2; ρ=1
10. y(x)=c0(1−3x2+3x28+x316+3x4128+⋯) =c0(1−x)3/2; ρ=1
11. y(x)=c0(1+x22!+x44!+x66!+⋯)+ c1(x+x33!+x55!+x77!+⋯) =c0 cosh x+c1 sinh x; ρ=+∞
12. y(x)=c0(1+(2x)22!+(2x)44!+(2x)66!+⋯)+ c12((2x)+(2x)33!+(2x)55!+(2x)77!+⋯) =c0 cosh 2x+c12 sinh 2x; ρ=∞
13. y(x)=c0(1−(3x)22!+(3x)44!−(3x)66!+⋯)+ c13(3x−(3x)33!+(3x)55!−(3x)77!+⋯) =c0 cos 3x+13c1 sin 3x; ρ=+∞
14. y(x)=x+c0(1−x22!+x44!−x66!+⋯) +(c1−1)(x−x33!+x55!−x77!+⋯) =x+c0 cos x+(c1−1) sin x; ρ=∞
15. (n+1)cn=0 for all n≧0, so cn=0 for all n≧0.
16. 2ncn=cn for all n≧0, so cn=0 for all n≧0.
17. c0=c1=0 and cn+1=−ncn for n≧1, thus cn=0 for all n≧0.
18. cn=0 for all n≧0
19. (n+1)(n+2)cn+2=−4cn; y(x)=32[(2x)−(2x)33!+(2x)55!−(2x)77!+⋯]=32sin 2x
20. (n+1)(n+2)cn+2=4cn; y(x)=2[1+(2x)22!+(2x)44!+(2x)66!+⋯]=2 cosh 2x
21. n(n+1)cn+1=2ncn−cn−1; y(x)=x+x2+x32!+x43!+x54!+⋯=xex
22. n(n+1)cn+1=−ncn+2cn−1; y=e−2x
23. As c0=c1=0 and (n2−n+1)cn+(n−1)cn−1=0 for n≧2, cn=0 for all n≧0