For an offspring to what a recessive trait, both parents must have at least one what allele in their genotype

For an offspring to have a recessive trait, both parents must have at least one recessive allele in their genotype

Explanation:

When an organism contains a pair of dissimilar alleles for a given trait it is said to be heterozygous. A heterozygous state contains one dominant  allele and a recessive allele. When two parents are heterozygous, the offspring will have a recessive trait. For example a cross between heterozygous tall plants.

      T           t

T     TT         Tt  

t     Tt           tt

complete the square on the right side of the equation;

-5(x + 0)^2 + 15

answer: d. y = -x^2 + 15