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.