The perfect square
Let's highlight the perfect square of the square three-member
$$- 5 x^{2} + \left(x 13 y + y^{2}\right)$$
Let us write down the identical expression
$$- 5 x^{2} + \left(x 13 y + y^{2}\right) = \frac{189 y^{2}}{20} + \left(- 5 x^{2} + 13 x y - \frac{169 y^{2}}{20}\right)$$
or
$$- 5 x^{2} + \left(x 13 y + y^{2}\right) = \frac{189 y^{2}}{20} - \left(\sqrt{5} x - \frac{13 \sqrt{5} y}{10}\right)^{2}$$
/ / ____\\ / / ____\\
| y*\13 - 3*\/ 21 /| | y*\13 + 3*\/ 21 /|
|x - -----------------|*|x - -----------------|
\ 10 / \ 10 /
$$\left(x - \frac{y \left(13 - 3 \sqrt{21}\right)}{10}\right) \left(x - \frac{y \left(13 + 3 \sqrt{21}\right)}{10}\right)$$
(x - y*(13 - 3*sqrt(21))/10)*(x - y*(13 + 3*sqrt(21))/10)
General simplification
[src]
$$- 5 x^{2} + 13 x y + y^{2}$$
$$- 5 x^{2} + 13 x y + y^{2}$$
Assemble expression
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$$- 5 x^{2} + 13 x y + y^{2}$$
Combining rational expressions
[src]
$$- 5 x^{2} + y \left(13 x + y\right)$$
Rational denominator
[src]
$$- 5 x^{2} + 13 x y + y^{2}$$
$$- 5 x^{2} + 13 x y + y^{2}$$
$$- 5 x^{2} + 13 x y + y^{2}$$
$$- 5 x^{2} + 13 x y + y^{2}$$