Karnaugh Map for Logic Function

Question

I have the following boolean function: F=(a1+b1)(a2+b2) and am trying to construct a K-map for it. This is what I have so far:

I'm relatively new to K-maps, so I'm not entirely convinced this is correct. Could someone please double check it for me?

Answer 1

While circling in Karnaugh map, you always have to make circles of 2^n size in each direction (1x1, 2x1, 4x1, 2x2, 4x4, ..., but never 1x3, 3x3, 5x3).

You need 4 circles 2x2 in your example.