Use the quadratic equation y = x2 + 3x + 9.

Where does the vertex of the parabola lie?
(Points : 5)
below the x-axis
above the x-axis
on the x-axis
on the y-axis

Question

Use the quadratic equation y = x2 + 3x + 9.

Where does the vertex of the parabola lie? 
(Points : 5)
       below the x-axis
       above the x-axis
       on the x-axis
       on the y-axis

barreraa · Answer

i think this one is A @sasogeek

nnesha · Answer

$$\huge\rm x=\frac{ -b }{ 2a }$$
formula to find x coordinate of vetex

barreraa · Answer

ok thanks but i just want to know if im right or wrong  @Nnesha

nnesha · Answer

nope that's incorrect 
substitute x value   y=x^2+3x+9 solve for y
 y is positive or negative ?

barreraa · Answer

i think its between B and D @Nnesha

nnesha · Answer

so which one do not guess :-)

nnesha · Answer

$$\huge\rm Ax^2+Bx+C=0$$ quadratic equation 
A leading coefficient 
C is constant term

barreraa · Answer

b above the x-axis @Nnesha

nnesha · Answer

is that an educated guess or are u 100% sure ?? :=)

barreraa · Answer

thanks for the help @Nnesha

nnesha · Answer

np :=)