Question

Срочно
x=1 y=3x+y
(x+y)2 степени-(3x-y)(3x+y)

Answer 1

${(x + y) }^{2} - (3x - y)(3x + y) = {x}^{2} + 2xy + {y}^{2} - ( {9x}^{2} - {y}^{2}) = {x}^{2} + 2xy + {y}^{2} - {9x}^{2} + {y}^{2} = - {8x}^{2} + 2xy + {2y}^{2}$