The perfect square
Let's highlight the perfect square of the square three-member
$$\left(x^{2} + 9 x\right) - 6$$
To do this, let's use the formula
$$a x^{2} + b x + c = a \left(m + x\right)^{2} + n$$
where
$$m = \frac{b}{2 a}$$
$$n = \frac{4 a c - b^{2}}{4 a}$$
In this case
$$a = 1$$
$$b = 9$$
$$c = -6$$
Then
$$m = \frac{9}{2}$$
$$n = - \frac{105}{4}$$
So,
$$\left(x + \frac{9}{2}\right)^{2} - \frac{105}{4}$$
/ _____\ / _____\
| 9 \/ 105 | | 9 \/ 105 |
|x + - - -------|*|x + - + -------|
\ 2 2 / \ 2 2 /
$$\left(x + \left(\frac{9}{2} - \frac{\sqrt{105}}{2}\right)\right) \left(x + \left(\frac{9}{2} + \frac{\sqrt{105}}{2}\right)\right)$$
(x + 9/2 - sqrt(105)/2)*(x + 9/2 + sqrt(105)/2)