Here are two steps from the derivation of the quadratic formula. what took place between the first step and the second step? a. completing the square b. taking the square root of both sides c. factoring a perfect square trinomial previous

Answer asap and if you do you will get brainliest. catherine buys a gallon of ice cream from the store. after taking it home, she eats a fifth of a gallon of ice cream. her sister eats some of the ice cream as well. if two-thirds of the original amount of ice cream is left, then what fraction of a gallon of ice cream did her sister eat?