Question

how does redshift support the idea that the universe had a beginning?

Explanation:

Redshift indicates that galaxies are moving away from us. By extrapolating this motion backward in time, all matter would have been at a single point - the Big - Bang, which is considered the beginning of the universe.

Answer:

Redshift shows galaxies are receding. Extrapolating backward, all matter was at a single point (Big - Bang), suggesting a beginning.