Well the mode is like the most set it numbers so
k = 0 means the parabola has one zero, because the vertex is just on the x-axis. k > 0 means the parabola has none zeros, because the vertex will be above the x-axis and it will not intersect the x - axis.
So the equation format you will be using is y=mx+b. m = slope and b = y int.
So since to join the membership you have to pay $25.00 that will be your y int. Because that is the balance you are starting with. And then since the times you are paying each month are remaining constant, your slope will be $14. Finally x = months or time. So your equation will be y=14(6)+25 or y=14x+25
