The perfect square
Let's highlight the perfect square of the square three-member
$$b^{2} + \left(- b 2 y - y^{2}\right)$$
Let us write down the identical expression
$$b^{2} + \left(- b 2 y - y^{2}\right) = - 2 y^{2} + \left(b^{2} - 2 b y + y^{2}\right)$$
or
$$b^{2} + \left(- b 2 y - y^{2}\right) = - 2 y^{2} + \left(b - y\right)^{2}$$
in the view of the product
$$\left(- \sqrt{2} y + \left(b - y\right)\right) \left(\sqrt{2} y + \left(b - y\right)\right)$$
$$\left(- \sqrt{2} y + \left(b - y\right)\right) \left(\sqrt{2} y + \left(b - y\right)\right)$$
$$\left(b + y \left(-1 + \sqrt{2}\right)\right) \left(b + y \left(- \sqrt{2} - 1\right)\right)$$
$$\left(b + y \left(-1 + \sqrt{2}\right)\right) \left(b + y \left(- \sqrt{2} - 1\right)\right)$$
General simplification
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$$b^{2} - 2 b y - y^{2}$$
/ / ___\\ / / ___\\
\b - y*\1 - \/ 2 //*\b - y*\1 + \/ 2 //
$$\left(b - y \left(1 - \sqrt{2}\right)\right) \left(b - y \left(1 + \sqrt{2}\right)\right)$$
(b - y*(1 - sqrt(2)))*(b - y*(1 + sqrt(2)))
Rational denominator
[src]
$$b^{2} - 2 b y - y^{2}$$
Assemble expression
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$$b^{2} - 2 b y - y^{2}$$
$$b^{2} - 2 b y - y^{2}$$
$$b^{2} - 2 b y - y^{2}$$
$$b^{2} - 2 b y - y^{2}$$
$$b^{2} - 2 b y - y^{2}$$
Combining rational expressions
[src]
$$b^{2} + y \left(- 2 b - y\right)$$