Solve by elimination 3x+3y=0 and -2x-y=0

Using the quadratic formula find the zeros of the given polynomial -5x^2+3x-11

The height of a flare fired from the deck of a ship in distress can be modeled by h(t)= -2(8t^2-52t-28), where h is the height of the flare above water and t is the time in seconds. a. find the time it takes the flare to hit the water.

How are algebraic expressions evaluated using substitution?