What is the x-coordinate of the vertex of the parabola whose equation is y = 3x2 + 9x?

hello :
y = 3x²+9x
= 3(x² + 3x )
= 3 ( x² +2(3/2)x +(3/2)²) -(3/2)²)
= 3((x+3/2)² -9/4)
y = 3 (x+3/2)² -27/4
the x-coordinate of the vertex is : - 3/2

Answer Link

SerenaBochenek SerenaBochenek · Answer 2 · 2019-03-26T07:37:37+01:00

Answer:

[tex]\text{The x-coordinate of vertex of parabola is -1.5}[/tex]

Step-by-step explanation:

Given the equation of parabola

[tex]y=3x^2+9x[/tex]

we have to find the x-coordinate of the vertex of the parabola.

The general form of equation of parabola is

[tex]ax^2+bx+c=0[/tex]

The x-coordinate of the vertex of the parabola can be calculated as

[tex]h=\frac{-b}{2a}[/tex]

Comparing the given equation with the general equation, we get

a=3, b=9, c=0

x-coordinate of the vertex of the parabola is

[tex]h=\frac{-9}{2(3)}=\frac{-3}{2}=-1.5[/tex]

The x-coordinate of vertex of parabola is -1.5