The perfect square
Let's highlight the perfect square of the square three-member
$$\left(y^{2} - y\right) + 7$$
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
$$a = 1$$
$$b = -1$$
$$c = 7$$
Then
$$m = - \frac{1}{2}$$
$$n = \frac{27}{4}$$
So,
$$\left(y - \frac{1}{2}\right)^{2} + \frac{27}{4}$$
General simplification
[src]
$$y^{2} - y + 7$$
/ ___\ / ___\
| 1 3*I*\/ 3 | | 1 3*I*\/ 3 |
|x + - - + ---------|*|x + - - - ---------|
\ 2 2 / \ 2 2 /
$$\left(x + \left(- \frac{1}{2} - \frac{3 \sqrt{3} i}{2}\right)\right) \left(x + \left(- \frac{1}{2} + \frac{3 \sqrt{3} i}{2}\right)\right)$$
(x - 1/2 + 3*i*sqrt(3)/2)*(x - 1/2 - 3*i*sqrt(3)/2)
Combining rational expressions
[src]
$$y \left(y - 1\right) + 7$$
Assemble expression
[src]
$$y^{2} - y + 7$$
Rational denominator
[src]
$$y^{2} - y + 7$$