Write an equation for a parabola with a focus at (0,5) and a directrix at x=-7?

Aboat's value over time is given as the function f(x) and graphed below. use a(x) = 400(b)x + 0 as the parent function. which graph shows the boat's value increasing at a rate of 25% per year?

Afactory adds 3 red drops and 2 blue drops of coloring to white paint to make each pint of purple paint. the factory will make 50 gallons of the purple paint.how many drops of red and blue coloring will the factory need in the 50 gallon batch of purple paint.

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?