Question

Find the vertex of the parabola with an equation y=-(x-2)(x-4)

Answer 1

Answer:

clearly a is not zero .now the given quadratic equation is ;

y = a(x -2)(x + 4) = a (x^2 + 2x -8)

= a(x + 1)^2 - 9 ==> ((y/a)+9) = (x+1)^2 or x^2 = y where x = (x+1) & y= ((y/a)+9) which is equation of a parabola with axis x = 0 or (x+1) = 0 and vertex x = 0 = y ==> (x+1) = 0 or x = - 1 & (y/a) + 9 = 0 or y = -9a . hence the vertex (c, d) = (-1, -9a) etc.