what is the vertext of x2 + 10x - 56

Answer 1

x = -b/2a = -10/2(1) = -5

y = (-5)² + 10(-5) - 56

y = 25 - 50 - 56

y = -81

(-5,-81)

Answer 2

Factor it

(x + 14)(x - 4)

Set equal to zero to find the x-intercepts

x = -14 and x = 4

Go halfway between these

x = -5

That is the x coordinate of the vertex.

To find the y coordinate of the vertex, plug in x = -5

(-5)² + 10(-5) - 56

25 - 50 - 56 = -81

So the vertex is at (-5, -81)

A simpler way that perhaps you may not have learned yet is to use the shortcut x = -b/2a where the quadratic equation is in the form ax² + bx + c = 0. In this case a = 1, b = 10, c = -56, so x = -10/(2*1) = -5. You still need to plug in -5 to find the y coordinate of the vertex though.