The perfect square
Let's highlight the perfect square of the square three-member
$$- 5 x^{2} + \left(- x 4 y - y^{2}\right)$$
Let us write down the identical expression
$$- 5 x^{2} + \left(- x 4 y - y^{2}\right) = - \frac{y^{2}}{5} + \left(- 5 x^{2} - 4 x y - \frac{4 y^{2}}{5}\right)$$
or
$$- 5 x^{2} + \left(- x 4 y - y^{2}\right) = - \frac{y^{2}}{5} - \left(\sqrt{5} x + \frac{2 \sqrt{5} y}{5}\right)^{2}$$
/ y*(-2 + I)\ / y*(2 + I)\
|x - ----------|*|x + ---------|
\ 5 / \ 5 /
$$\left(x - \frac{y \left(-2 + i\right)}{5}\right) \left(x + \frac{y \left(2 + i\right)}{5}\right)$$
(x - y*(-2 + i)/5)*(x + y*(2 + i)/5)
General simplification
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$$- 5 x^{2} - 4 x y - y^{2}$$
$$- 5 x^{2} - 4 x y - y^{2}$$
$$- 5 x^{2} - 4 x y - y^{2}$$
Combining rational expressions
[src]
$$- 5 x^{2} + y \left(- 4 x - y\right)$$
$$- 5 x^{2} - 4 x y - y^{2}$$
$$- 5 x^{2} - 4 x y - y^{2}$$
Assemble expression
[src]
$$- 5 x^{2} - 4 x y - y^{2}$$
Rational denominator
[src]
$$- 5 x^{2} - 4 x y - y^{2}$$