the graph of the quadratic function f(x)=4(x-1) (x-5) is a parabola with vertex at point (a,b). Find value of ab

Answer 1

Expanding the function, we get f(x) = 4x2 -24x + 20 represented by ax2 + bx + c

we know that the x value at the vertex is given as -b/2a = -(-24)/(2*4) = 3

Substituting this x value, f(x) = 4(3)2 -24(3) + 20 = -16

So the vertex = (3,-16)