What is the first step when rewriting y = 3x2 9x – 18 in the form y = a(x – h)2 k?

A quadratic equation has the general form of: 

y=ax² + bx + c

It can be converted to the vertex form in order to determine the vertex of the parabola. It has the standard form of:

y = a(x+h)² - k

This can be done by completing a square. The steps are as follows:

y = 3x2 + 9x – 18
y = 3(x2 + 3x) – 18
y + 27/4= 3(x2 + 3x+ 9/4) – 18 
y = 3(x2 + 3/2)^2 – 99/4

Therefore, the first step is to group terms with the variable x and factoring out the coefficient of x^2.