Skateboard Revenue: A skateboard shop sells about 50 skateboards per week for the price advertised. For each $1 decrease in price, about 1 more skateboard per week is sold. The shop's revenue can be modeled by y=(70-x) (50+x). Use vertex form to find how the shop can maximize weekly revenue.
[I can get this into vertex form, but I'm not understanding how to read the vertex form of the equation to answer the question]
Well, the form [tex]ax^2+bx+c[/tex] gives the maximum (if a<0) at coordinates [tex](\frac{-b}{2a};\frac{-\Delta}{4a})[/tex], where [tex]\Delta=b^2-4ac[/tex]. If a>0, the same formula gives the minimum (there's no maximum)
