-х-х=7
-2х=7
х=7:(-2)
х=-3,5
(8.1*3.5*1*2-3*1)-(7.1*1*2*3.5+3.5)=(56.7-3)-(49.7+3.5)=53.7-53.2=0.5
( y - 3 )^2 - 4( 3 - y ) = 0
( y - 3 )( y - 3 + 4 ) = 0
( y - 3 )( y + 1 ) = 0
y - 3 = 0
y = 3
y + 1 = 0
y = - 1
Ответ 3 ; - 1
(a-b)^2(a+b)^5+(a+b)^2(a-b)^5 =(a+b)^7+(a+b)^7=2((a+b)^7)
X³+8y³-2x²y-4xy²=x³+(2y)³-2xy(x+2y)=
=(x+2y)(x²-2xy+4y²)-2xy(x+2y)=(x+2y)(x²-2xy+4y²-2xy)=
=(x+2y)(x²-4xy+4y²)=(x+2y)(x-2y)²