Question

Write the equation of the quadratic function with roots -1 and 1 and a vertex at (0,-3)

Answer 1

First I recommend looking at what each coefficient of a quadratic function does to the graph (use wolframalpha and just type in quadratic formulas and look at their graphs)

First, roots are -1 and +1 so,
(x-1)(x+1)

expand it,

x^2 - 1

now we need a vortex of (0,-3), that is the coefficient on x^2 that dictates that so,

3x^2-1

done