3(4x-y)^2-2(x-y)(x+y)+4(x+3y)^2
3(16x^2-8xy+y^2)-2(x^2-y^2)+4(x^2+6xy+9у^2)
48х^2-24ху+3у^2-2х^2+2у^2+4х^2+24ху+36у^2
50х^2+41у^2
Если х=-1/5; у=-1, то 50(-1/5)^2+41•(-1)^2
50•0,04+41=2+41=43
15x² -11x =0
x(15x -11) =0
x =0
15x -11 =0
15x =11
x =11/15
ответ: x =0; x =11/15
D=3² - 4 x 7 x (-1) = 9 + 28 = 37
Х^2y - 2y + xy^2 - 2x=
=(x^2y +xy^2)-(2y+2x)=
=xy(x+y) - 2(y+x)=
=(x+y)(xy-2)