Question

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

Answer 1

$[tex]3y(6y+2x) - (x+3y)^{2} = 18y^{2} + 6xy - ( x^{2} + 6xy + 9y^{2} ) = \ =18y^{2} + 6xy - x^{2} - 6xy - 9y^{2} = 9y^{2} - x^{2}$

Если $x= sqrt{2}, y = sqrt{7},$ то $9y^{2} - x^{2} = 9 sqrt{7^{2} } - sqrt{ 2^{2} } = 9*7 - 2=61$