(3/2x^2-5xy+y^2)-[-3xy+2(1/4x^2-xy)+2/3y^2]，其中x=1,y=-2 化简求值

---

(2分之3x的2次方-5xy+y的2次方)-【-3xy+2(4分之一x的隐猜2次方-xy)+3分之2y的薯睁2次方】
=3/2x²-5xy+y²-(-3xy+1/2x²-2xy+2/3y²数携岁)
=3/2x²-5xy+y²+5xy-1/2x²-2/3y²
=x²-1/3y²

---

(3/2x^2-5xy+y^2)-[-3xy+2(1/4x^2-xy)+2/3y^2]
=3/2x²-5xy+y²+3xy-2/3y²蚂兄核+1/尘或2x²-2xy
=2x²闷掘-4xy+1/3y²

---