Which point gives the vertex of f(x) = x2 - 4x + 21?

Find the equation of a line that is perpendicular to line g that contains (p, q). coordinate plane with line g that passes through the points negative 3 comma 6 and 0 comma 5 3x − y = 3p − q 3x + y = q − 3p x − y = p − q x + y = q − p

Yo need asap pls ! markin da brainiest too !

How do you do the foil method with polynomials?