12. the relation fn+2 = fn+1 + fn can be rewritten as fn+1 = fn+2 - fn. use this form to find a compact expression for fa + fa+2 + fa+4 + fa+6 + + fa+2m.

2. what two items do autotrophs take from the environment to produce their food? 3. what are the two items that are released during transpiration from leaves? 4. what are the two membranes of the system? a.what are the two stages of photosynthesis? what are the two parts of photosynthesis?