The perfect square
Let's highlight the perfect square of the square three-member
$$\left(- 4 y^{2} - 6 y\right) + 12$$
To do this, let's use the formula
$$a y^{2} + b y + c = a \left(m + y\right)^{2} + n$$
where
$$m = \frac{b}{2 a}$$
$$n = \frac{4 a c - b^{2}}{4 a}$$
In this case
$$a = -4$$
$$b = -6$$
$$c = 12$$
Then
$$m = \frac{3}{4}$$
$$n = \frac{57}{4}$$
So,
$$\frac{57}{4} - 4 \left(y + \frac{3}{4}\right)^{2}$$
General simplification
[src]
$$- 4 y^{2} - 6 y + 12$$
/ ____\ / ____\
| 3 \/ 57 | | 3 \/ 57 |
|x + - - ------|*|x + - + ------|
\ 4 4 / \ 4 4 /
$$\left(x + \left(\frac{3}{4} - \frac{\sqrt{57}}{4}\right)\right) \left(x + \left(\frac{3}{4} + \frac{\sqrt{57}}{4}\right)\right)$$
(x + 3/4 - sqrt(57)/4)*(x + 3/4 + sqrt(57)/4)
Rational denominator
[src]
$$- 4 y^{2} - 6 y + 12$$
Combining rational expressions
[src]
$$2 \left(y \left(- 2 y - 3\right) + 6\right)$$
Assemble expression
[src]
$$- 4 y^{2} - 6 y + 12$$