3y(6y+2x)-(x+3y)2 при x-корень 2 и y-корень 7

[latex][latex]3y(6y+2x) - (x+3y)^{2} = 18y^{2} + 6xy - ( x^{2} + 6xy + 9y^{2} ) = \\ =18y^{2} + 6xy - x^{2} - 6xy - 9y^{2} = 9y^{2} - x^{2} [/latex] Если [latex]x= \sqrt{2}, y = \sqrt{7}, [/latex] то [latex] 9y^{2} - x^{2} = 9 \sqrt{7^{2} } - \sqrt{ 2^{2} } = 9*7 - 2=61 [/latex]