Respuesta :
Answer:
Expressing the equation in vertex form we have;
[tex]y=9(x+6)^2-396[/tex]Vertex at (-6,-396)
Explanation:
We want to convert the quadratic equation given to vertex form by completing the square.
[tex]y=9x^2+108x-72[/tex]The vertex form of quadratic equation is of the form;
[tex]f(x)=a(x-h)^2+k[/tex]To do this by completing the square;
Firstly, let's add 72 to both sides of the qeuation;
[tex]\begin{gathered} y+72=9x^2+108x-72+72 \\ y+72=9x^2+108x \end{gathered}[/tex]Them we will add a number that can make the right side of the equation a complete square to both sides;
Adding 324 to both sides;
[tex]\begin{gathered} y+72+324=9x^2+108x+324 \\ y+396=9x^2+108x+324 \end{gathered}[/tex]factorizing the right side of the equation;
[tex]\begin{gathered} y+396=9(x^2+12x+36) \\ y+396=9(x+6)(x+6) \\ y+396=9(x+6)^2 \end{gathered}[/tex]Then, let us subtract 396 from both sides;
[tex]\begin{gathered} y+396-396=9(x+6)^2-396 \\ y=9(x+6)^2-396 \end{gathered}[/tex]Therefore, expressing the equation in vertex form we have;
[tex]y=9(x+6)^2-396[/tex]Vertex at (-6,-396)
