| Line 11: | Line 11: | ||
Notice that | Notice that | ||
| − | <math>(e^z f)''=e^zf +2e^zf'+e^zf''=2(e^zf + e^zf')=(e^zf)'.</math> | + | <math>(e^z f)''=e^zf +2e^zf'+e^zf''=2(e^zf + e^zf')=2(e^zf)'.</math> |
| − | Let <math>g=e^zf.</math> | + | Let <math>g=e^zf.</math> Then g'=2g. |
Revision as of 03:37, 23 September 2009
Homework 4
Hint for IV.6.3 --Steve Bell
We assume $ f''=f $ on $ \mathbb C $.
Notice that
$ (e^z f)''=e^zf +2e^zf'+e^zf''=2(e^zf + e^zf')=2(e^zf)'. $
Let $ g=e^zf. $ Then g'=2g.
