An tetraploid plant undergoes self-fertilization. At least two dominant A alleles are needed to obtain the dominant phenotype. At what frequency will progeny with the dominant phenotype appear?

The frequency will be  35/36

Explanation:

An tetraploid plant will only produce a gamete which will be Aa, but during a self crossing a progeny with genotype will be produced and this will happen at a frequency of 35/36 and this simply means that the progenies produced during the self crossing  will all have a dominant phenotype

this is math not biology xd