If you check the TL972 datasheet (www.ti.com/lit/ds/symlink/tl972.pdf) on page 8 Figure 5, the output impedance at 5V is less than 0.1 ohm, so the total Zout is:
Zout = R6(4.7K) + 01ohm = 4.7K
Meaning that the output impedance at pin A0 is determined by R6 (4.6K).