x=5-2√6,y=5+2√6x+y = (5-2√6)+(5+2√6) = 10xy = (5-2√6)(5+2√6) = 5²-(2√6)² = 13x²-5xy+3y²= 3(x+y)²-11xy= 3*10²-11= 300-11= 289