= Solution
A <kinematic redshift> is the <relativistic Doppler effect> arising from relative motion of emitter and receiver. In a local inertial frame, recession decreases the received <frequency> and approach increases it. A <cosmological redshift> instead compares photons emitted and received by comoving observers at different <cosmic times>: expansion of the <scale factor> stretches their <wavelengths>. It exists even when both observers have zero <peculiar velocity>. Both are frequency ratios measured by observers, but a large <cosmological redshift> should not be inserted into a flat-spacetime radial-speed formula to define the galaxy's unique recession speed.
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