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
$$5 x^{2} + \left(x 4 y - y^{2}\right) = - \frac{9 y^{2}}{5} + \left(5 x^{2} + 4 x y + \frac{4 y^{2}}{5}\right)$$
or
$$5 x^{2} + \left(x 4 y - y^{2}\right) = - \frac{9 y^{2}}{5} + \left(\sqrt{5} x + \frac{2 \sqrt{5} y}{5}\right)^{2}$$
in the view of the product
$$\left(- \sqrt{\frac{9}{5}} y + \left(\sqrt{5} x + \frac{2 \sqrt{5}}{5} y\right)\right) \left(\sqrt{\frac{9}{5}} y + \left(\sqrt{5} x + \frac{2 \sqrt{5}}{5} y\right)\right)$$
$$\left(- \frac{3 \sqrt{5}}{5} y + \left(\sqrt{5} x + \frac{2 \sqrt{5}}{5} y\right)\right) \left(\frac{3 \sqrt{5}}{5} y + \left(\sqrt{5} x + \frac{2 \sqrt{5}}{5} y\right)\right)$$
$$\left(\sqrt{5} x + y \left(- \frac{3 \sqrt{5}}{5} + \frac{2 \sqrt{5}}{5}\right)\right) \left(\sqrt{5} x + y \left(\frac{2 \sqrt{5}}{5} + \frac{3 \sqrt{5}}{5}\right)\right)$$
$$\left(\sqrt{5} x - \frac{\sqrt{5} y}{5}\right) \left(\sqrt{5} x + \sqrt{5} y\right)$$
/ y\
(x + y)*|x - -|
\ 5/
$$\left(x - \frac{y}{5}\right) \left(x + y\right)$$
General simplification
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$$5 x^{2} + 4 x y - y^{2}$$
Rational denominator
[src]
$$5 x^{2} + 4 x y - y^{2}$$
$$5 x^{2} + 4 x y - y^{2}$$
$$\left(x + y\right) \left(5 x - y\right)$$
$$5 x^{2} + 4 x y - y^{2}$$
Combining rational expressions
[src]
$$5 x^{2} + y \left(4 x - y\right)$$
Assemble expression
[src]
$$5 x^{2} + 4 x y - y^{2}$$
$$5 x^{2} + 4 x y - y^{2}$$