The form of the quadratic function is
[tex]f(x)=ax^2+bx+c[/tex]
y-intercept (0, c)
Its vertex is (h, k), where
[tex]\begin{gathered} h=\frac{-b}{2a} \\ k=f(h) \end{gathered}[/tex]
Since the given function is
[tex]f(x)=x^2+3x-4[/tex]
Compare it with the form above to find the values of a, b, and c
a = 1
b = 3
c = -4
The y-intercept is (0, -4)
That means the parabola will cut the y-axis at the point (0, -4)
We have 2 answers have y-intercept (0, -4)
The first and the last
To find the correct answer, we have to find the vertex (h, k)
By using the rule of h above
[tex]h=\frac{-3}{2(1)}=-\frac{3}{2}=-1.5[/tex]
The vertex point has x-coordinate = -1.5
Only the last graph has a vertex with x-coordinate = -1.5
Then the answer is the last graph
