（4x-3y)(4x+3y)-(4x-y)^2+(x+5y)*(2y+1)
=(16x²-9y²)-(16x²-8xy+y²)+(2xy+x+10y²+5y)
=10xy+x+5y
x=2,y=-1/5
原式
=10xy+x+5y
=10×2×(-1/5)+2+5×(-1/5)
=-3解方程（x-1/3)^2-(x+1/3)(x-1/3)=1/3呢？不会啊急急急（x-1/3)^2-(x+1/3)(x-1/3)=1/3x²-2/3x+1/9-x²+1/9-1/3=0x=-1/6