A very easy way to find out if a graph is a function is to use the vertical line test.
Look at each graph and mentally draw a vertical line that goes through each of its points.
If that line goes through more than one point (2, 3, 4...) then that graph is not a function.
That's because a function, is an equation for which each input (x value) has exactly one output (y value). There cannot be two points of the same x value, with two different y values.
Hello : <span>f(x)=x²+4x-5 </span><span>The axis of symmetry for a function in the form f(x)=x^2+4x-5 is x=-2 : </span>f(x) = (x+2)² + b f(x) x²+4x+4+b= x² +4x-5 4+b= -5 b = -9 the vertex is : (2 , -9)