【（x-y）的平方分之x】*【（x+y）分之（x的平方-y的平方）】+【（x+y）分之（x的平方+2）-2】
=x/(x-y)^2 *(x^2-y^2)/(x+y) +x^2/(x+y) -2
=x/(x-y)^2 *(x+y)(x-y)/(x+y) +x^2/(x+y) -2
=x/(x-y) +x^2/(x+y) -2
联立方程组x+2y=3
x-y=2
解得：y=1/3,x=7/3
故原式=x/(x-y) +x^2/(x+y) -2
=(7/3)/(7/3 -1/3) +(7/3)^2 /(7/3+1/3) -2
=7/6 +49/24 -2
=(28+49-48)/24
=29/24