<span>1.5х-9у-(у+1.5у)=5x -11.5y = 5*0.781 - 11.5*0.9= -6.445</span>
X=-7.8
.........................................
(3xy² + 5x²y² - 7xy + 7 + 11) + (- 2xy² + x²y² + 2xy + y - 2) =
= <u>3xy²</u> + 5x²y²<em> - 7xy</em> + 18 - <u>2xy²</u> + x²y² <em>+2xy</em> + y - 2 =
= 6x²y² + xy² - 5xy + y + 16