已知x+y=5,xy=3,x³+y³=(x+y)(x²-xy+y²),则1/x³+1/y³=?解,得：因为x+y=5所以(x+y)^2==25x^2+2xy+y^2==25所以x^2-xy+y^2+3xy==25x^2-xy+y^2==25-3xyx^2-xy+y^2==25-9x^2-xy+y^2==6所以x...