Final answer:
To solve the equation -y² = 5y, the equation is rearranged to -y² - 5y = 0, then factored to y(-y - 5) = 0, which yields two solutions: y = 0 or y = -5.
Step-by-step explanation:
To solve the equation for y given -y² = 5y, we need to rearrange the equation and factor y out. We can rewrite the equation as -y² - 5y = 0. Factoring out a y from each term, we get y(-y - 5) = 0. Now, we can use the zero product property which states that if a product of two factors is zero, then at least one of the factors must be zero. This gives us two possible solutions for y: either y = 0 or -y - 5 = 0, which simplifies to y = -5 upon adding 5 to both sides.