Solution...1. Rb6! to prevent Qa7. Then if 1... Ka2 2. Qa8#.Which is faster than 1. Rb5 Ka2 and now 2. Ra6# is not possible because of the pin on the rook, so 2. Qa8+ Qa7 3. Qxa7# takes a move longer.So after 1. Rb6! if Black moves the queen then 2. Ra5#. For example, after 1... Qc1 2. Ra5 is mate because of the pin on the queen.
Solution...
ReplyDelete1. Rb6! to prevent Qa7. Then if 1... Ka2 2. Qa8#.
Which is faster than 1. Rb5 Ka2 and now 2. Ra6# is not possible because of the pin on the rook, so 2. Qa8+ Qa7 3. Qxa7# takes a move longer.
So after 1. Rb6! if Black moves the queen then 2. Ra5#. For example, after 1... Qc1 2. Ra5 is mate because of the pin on the queen.