Answer:
positive point: [tex](0,\sqrt{2})[/tex]
negative points: [tex](0,-\sqrt{2})[/tex].
Step-by-step explanation:
Factorize the given expression.
[tex]f(x)=-2x^2+4\\f(x)=-2(x^2-2)\\f(x)=-2(x-\sqrt2)(x+\sqrt{2})[/tex]
Set the function equals to zero.
[tex]-2(x-\sqrt2)(x+\sqrt{2})=0\\x=\sqrt{2}, -\sqrt{2}[/tex]
So, the positive point is [tex](0,\sqrt{2})[/tex] and negative points is [tex](0,-\sqrt{2})[/tex].
