Question

How do you tell whether the graph opens up or down, find the vertex, and find the axis of symmetry of y=(x+2)(x−1)?

Answer 1

if the coefficient of x^2 is positive then the curve opens up and if it is negative , the curve opens down.

$\frac{dy}{dx} = x + 2 + x - 1$

if

$2x + 1 = 0$

then

$x = \frac{ - 1}{2}$

vertex is (-1/2,-9/4)

axis of symmetry is 2x+1=0